The Strait of Bonifacio Particularly Sensitive Sea Area is the PSSA designated by the International Maritime Organization through Resolution MEPC.204(62), adopted on 15 July 2011 at the 62nd session of the Marine Environment Protection Committee. The strait separates the southern tip of Corsica (France) from the northern coast of Sardinia (Italy) and is roughly 11 km wide at its narrowest, a constricted, current-swept and reef-strewn passage that carries dense ferry, leisure and merchant traffic between the western and central Mediterranean. France and Italy proposed the PSSA jointly, the only PSSA either state co-sponsors, and the designation made the strait the first Mediterranean PSSA, predating the North-Western Mediterranean PSSA of 2023 by twelve years. The Associated Protective Measures are recommendatory rather than mandatory because the strait is an international strait under the United Nations Convention on the Law of the Sea: the package comprises a France-Italy recommendation that ships carrying dangerous or polluting cargoes in bulk take a qualified pilot, a recommendation that loaded tankers and gas carriers avoid the strait and route south of Sardinia or north of Corsica, and the pre-existing BONIFREP mandatory ship reporting system in force since 1 December 1998. The PSSA reinforces the discharge restrictions of the MARPOL Convention, the Annex I Mediterranean oil Special Area, the Annex V garbage Special Area, and from 1 May 2025 the new Mediterranean Sulphur Emission Control Area. It follows the model set by the Wadden Sea PSSA and the Galapagos PSSA and the framework of the PSSA overview. Because the Bonifacio PSSA is a navigational designation and not a quantitative one, there is no single companion calculator; route-planning support is available through the ship voyage planning and routing library and the calculator catalogue.
Background: the PSSA framework and why Bonifacio qualifies
A Particularly Sensitive Sea Area is an area the IMO recognizes as needing special protection through IMO action because of recognized ecological, socio-economic or scientific significance and its vulnerability to damage from international shipping. The operative instrument is IMO Assembly Resolution A.982(24) of 1 December 2005, the Revised Guidelines for the Identification and Designation of PSSAs, as amended by Resolution MEPC.267(68) of 15 May 2015. A coastal state, or two states acting jointly as France and Italy did here, submits a documented case to the Marine Environment Protection Committee under three criterion families: ecological, social-cultural-economic, and scientific-educational. The proposal must be paired with at least one Associated Protective Measure drawn from an existing IMO instrument, and that is where the legal teeth come from. PSSA status by itself confers no enforceable obligation on a passing ship.
The framework was first applied to the Great Barrier Reef by Resolution MEPC.44(30) of 16 November 1990, then to the Wadden Sea by Resolution MEPC.101(48) in 2002, the first multi-state PSSA. The Bonifacio designation of 2011 is the second jointly proposed PSSA after the Wadden Sea, and it is structurally different from both of those. The Great Barrier Reef and Wadden Sea PSSAs rest on routeing and reporting measures the coastal states can enforce inside their own territorial seas and exclusive economic zones. Bonifacio cannot rely on the same toolset, because the strait is an international strait used for navigation between one part of the high seas or an exclusive economic zone and another, and that triggers the transit-passage regime of UNCLOS Part III. That single legal fact shapes every Associated Protective Measure in the resolution.
The case for Bonifacio under the A.982(24) criteria is strong on all three counts. Ecologically the strait holds extensive Posidonia oceanica seagrass meadows, a priority habitat under European Union law, together with coralligenous reefs, important seabird colonies on the surrounding islets, and a cetacean population that links it to the wider PELAGOS Sanctuary for Mediterranean Marine Mammals. Socio-economically it supports artisanal fisheries, a high-value tourism economy on both coasts, and the cultural landscape of the Lavezzi and Cerbicale archipelagos. Scientifically it is one of the most studied marine corridors in the western Mediterranean and is managed as a transboundary protected area straddling two member states.
Geography of the strait
The Strait of Bonifacio runs roughly east to west for about 19 km between the cliffs of Bonifacio on the Corsican side and the Gallura coast of Sardinia. At its narrowest the navigable channel is around 11 km wide, but the effective deep-water fairway is far tighter once the islands, shoals and reefs are removed from the chart. The Lavezzi Islands and the Cerbicale Islands lie on the French side and the La Maddalena archipelago on the Italian side, scattering granite islets, drying rocks and shallow banks across the approaches. The Lavezzi group itself is notorious: the French frigate Semillante was lost there in 1855 with more than 700 dead, a wreck still cited in the strait’s risk literature.
The hydrography compounds the hazard. The strait acts as a venturi between two basins, so a moderate Mediterranean wind funnels into strong surface currents that commonly run at 2 to 4 knots and can reach higher in gale conditions. The dominant wind is the westerly to north-westerly, the Libeccio and the Mistral that spills down from the Gulf of Lion, and it can drive short, steep seas through the constriction with little warning. A loaded tanker with limited maneuvering margin in a 6 nm channel, set down on a reef by a beam current in failing visibility, is the exact casualty the PSSA is built to prevent.
Traffic is heavy and mixed. The strait carries a year-round ferry service between Corsica and Sardinia, a summer surge of leisure craft and charter yachts, fishing vessels working both coasts, and a stream of merchant traffic, including tankers, taking the strait as a shortcut between the western Mediterranean and the Tyrrhenian Sea. Before the protective measures, that merchant flow included loaded crude and product tankers threading an 11 km gap full of rocks. The shortcut saves time against the open routes around Sardinia or Corsica, and that economic pull is precisely why a recommendation alone, without a physical barrier, is the policy tool available to the two states.
Casualty record and the road to designation
The strait’s reputation as a ship trap is old and well documented, and the casualty record is the empirical backbone of the PSSA proposal. The wreck of the French naval transport Semillante on the Lavezzi reefs on 15 February 1855, with the loss of more than 700 soldiers and crew bound for the Crimea, remains the most-cited disaster and the reason the Lavezzi cemetery still marks the strait on every pilot chart. Through the twentieth century the strait accumulated a steady tally of groundings, collisions and near-misses involving merchant ships, ferries and fishing vessels working the constricted fairway in current and reduced visibility.
The casualty that crystallized the political will was a tanker incident in the strait in 1993, when a laden product tanker grounded and spilled in the approaches, drawing French and Italian attention to the consequence of a loaded-tanker casualty inside what was becoming a transboundary marine reserve. The two states responded first with the bilateral measures that became BONIFREP, secured at the IMO and in force from 1 December 1998, and the recommendation discouraging dangerous-cargo transits. Those measures were the precursor to the PSSA: France and Italy had already built the reporting-and-recommendation framework over the decade before designation, so the 2011 PSSA resolution consolidated and gave an IMO label to a regime the two states had been operating for years.
The decade between the BONIFREP framework and the PSSA designation also saw the legal architecture of the marine park fall into place: the French Bouches de Bonifacio nature reserve in 1999, the Italian La Maddalena national park already running from 1994, and the PELAGOS cetacean sanctuary agreement signed in 1999. By the time France and Italy submitted the PSSA proposal, the strait had a documented ecological case, a documented casualty history, and an operating set of protective measures. The PSSA designation tied those threads together under the A.982(24) Guidelines and gave the recommendations the recognition of the IMO, which is what the resolution adds to the pre-existing national and bilateral framework.
The Bouches de Bonifacio international marine park
The transboundary protected area underpinning the ecological case is built from two national parks that France and Italy manage in concert. On the French side the Reserve Naturelle des Bouches de Bonifacio, created in 1999, covers roughly 80,000 hectares of the Corsican strait waters and is one of the largest marine nature reserves in metropolitan France. On the Italian side the Parco Nazionale dell’Arcipelago di La Maddalena, established in 1994, protects the Sardinian islands and surrounding waters. The two are coordinated through the Parc Marin International des Bouches de Bonifacio, set up as a European Grouping of Territorial Cooperation in 2012, the year after the PSSA designation, to give the cross-border park a single legal management body.
The habitat the park exists to protect is Posidonia oceanica, the endemic Mediterranean seagrass that forms dense underwater meadows on the strait’s sand and rock substrates. Posidonia meadows are slow-growing, with rhizomes that build over centuries, and they anchor an entire benthic food web while stabilizing sediment and oxygenating the water column. They are a priority natural habitat type under the European Union Habitats Directive of 1992, and physical damage to a meadow (from an anchor, a grounding, or a spill) takes decades to recover. The strait also holds coralligenous formations, maerl beds and submarine caves, each a slow-recovery habitat.
The fauna case is built on cetaceans and seabirds. The strait sits at the western edge of the PELAGOS Sanctuary, the 87,500 square kilometre cetacean reserve established by France, Italy and Monaco under an agreement signed in 1999 and linked to the Barcelona Convention’s specially protected area regime. Fin whales, striped dolphins, bottlenose dolphins and sperm whales use the wider sanctuary, and the strait is a movement corridor between the Tyrrhenian and the Ligurian-Provencal basin. The surrounding islets host breeding colonies of Cory’s shearwater, the Mediterranean shag and Audouin’s gull, a globally restricted-range species. Spill impact on a seabird colony in the breeding season is one of the documented vulnerabilities the proposal cited.
MEPC.204(62) designation
France and Italy submitted the joint PSSA proposal to MEPC, and the committee designated the Strait of Bonifacio as a Particularly Sensitive Sea Area by Resolution MEPC.204(62), adopted on 15 July 2011 at MEPC 62. The proposal had been developed over the preceding sessions and was considered against the A.982(24) Revised Guidelines then in force, before the MEPC.267(68) amendments of 2015. The resolution sets out the geographic scope of the PSSA, recites the ecological, socio-economic and scientific attributes that satisfy the identification criteria, documents the vulnerability to international shipping, and records the Associated Protective Measures the two states put forward.
The Associated Protective Measures themselves are split between the IMO instruments. The mandatory ship reporting system, BONIFREP, was already an adopted SOLAS Chapter V routeing-and-reporting measure, in force since 1998, so the PSSA designation incorporated an existing measure rather than adopting a new one. The pilotage and avoidance elements are recommendations issued by France and Italy and recognized by the IMO, rather than mandatory IMO routeing measures, because of the international-strait constraint discussed below. This is the central feature that distinguishes Bonifacio from a PSSA whose APMs are mandatory Areas To Be Avoided: here the most important navigational measures are recommendatory by legal necessity.
The strait is one of only two Mediterranean PSSAs. The second, the North-Western Mediterranean Sea PSSA covering the Ligurian-Provencal cetacean corridor, was designated by Resolution MEPC.380(80) on 7 July 2023, twelve years later, and its principal protective measure is a recommendatory speed reduction to reduce whale strikes. The two Mediterranean PSSAs are geographically adjacent through the PELAGOS sanctuary and address complementary risks: Bonifacio the grounding-and-spill risk in a narrow strait, the north-western PSSA the ship-strike risk across an open cetacean feeding ground.
APM 1: recommendatory pilotage for dangerous-cargo ships
The first and most-cited Associated Protective Measure is the joint France-Italy recommendation that ships carrying dangerous or polluting goods in bulk take a qualified maritime pilot for the passage of the strait. The recommendation targets the high-consequence traffic: loaded crude and product oil tankers, chemical tankers carrying MARPOL Annex II noxious liquid substances, and liquefied gas carriers. The reasoning is direct. A pilot with local knowledge of the current set, the reef positions and the traffic pattern materially reduces the grounding probability in an 11 km channel where a navigational error has no recovery margin.
The legal status of this measure is the heart of the Bonifacio case and a frequent source of confusion. France and Italy cannot make pilotage compulsory for a foreign ship merely transiting the strait, because that would conflict with the transit-passage regime of UNCLOS Part III, under which ships of all states enjoy the right of continuous and expeditious transit through straits used for international navigation. A coastal state bordering such a strait may adopt sea lanes and traffic separation schemes (UNCLOS Article 41) but only as proposed to and adopted by the competent international organization, the IMO, and it cannot impose a pilotage requirement that would in practice deny or impair the right of transit passage. So the measure is framed as a strong recommendation, recognized by the IMO in the PSSA resolution, rather than as a mandatory rule binding on every flag.
The recommendation is not toothless. Both states give it force for their own flags and for ships calling at their ports through national legislation and port-state powers. France applies pilotage and routing rules to French-flag ships and to ships bound to or from French ports under its merchant-shipping code, and Italy does the same through its navigation code and the port authority system. The recommendation also feeds insurance, charter-party and operator-policy practice: a prudent owner of a loaded tanker who declines a recommended pilot in a strait where a PSSA documents the grounding risk would face a difficult conversation with underwriters after a casualty. The practical compliance rate among large laden tankers is high, but the measure remains, for the transiting foreign ship in pure transit passage, a recommendation.
APM 2: recommendation that loaded tankers and gas carriers avoid the strait
The second measure is the recommendation that certain ships avoid the strait altogether and use the open routes south of Sardinia or north of Corsica. The recommendation is aimed at the heaviest-consequence vessels, loaded oil tankers, chemical tankers and gas carriers above defined size, and reflects a simple risk logic: the surest way to eliminate a grounding-and-spill casualty in the strait is to keep the cargo out of the strait. A laden very large crude carrier transiting the western Mediterranean has open-water alternatives that add modest distance and time, and the recommendation asks operators to weigh that cost against the consequence of a spill onto a Posidonia meadow inside an international marine park.
Like the pilotage measure, this is a recommendation and not a prohibition, for the same UNCLOS reason. France and Italy could not adopt a mandatory Area To Be Avoided that excluded foreign ships from an international strait without impairing transit passage, so the IMO resolution recognizes the avoidance recommendation rather than adopting a binding ATBA of the kind used in the Galapagos PSSA, where the surrounding waters are not an international strait and the coastal state could secure a mandatory ATBA. The Bonifacio case is the textbook illustration that the strength of a PSSA’s protective measures depends on the legal status of the waters, not on the severity of the ecological risk.
The avoidance recommendation interacts with the local fuel-quality measures the two states layer on top of the PSSA. The Italian region of Sardinia adopted a regional regulation, around the time of the PSSA designation, restricting the carriage of heavy fuel oils by ships transiting the Sardinian waters of the strait, intended to limit the worst-case spill product. Measures of this kind, adopted under regional or national law rather than under the IMO, sit alongside the PSSA and reinforce its purpose, but they raise the same UNCLOS questions about enforceability against a foreign ship in transit, and they are best understood as part of the coastal states’ own-flag and port-state toolkit rather than as binding international rules.
APM 3: BONIFREP mandatory ship reporting
The third measure is the mandatory ship reporting system BONIFREP, which predates the PSSA by more than twelve years. BONIFREP was adopted by the IMO as a ship reporting system under SOLAS Chapter V Regulation 11 and entered into force on 1 December 1998. It is one of the relatively small set of mandatory IMO reporting systems, and it is the one genuinely mandatory navigational measure in the Bonifacio package, lawful even for foreign ships in transit because a reporting requirement, unlike a pilotage or routing prohibition, does not deny or impair the right of transit passage.
Under BONIFREP a ship of 300 gross tonnage and above transmits a report on entering the reporting area at either end of the strait. The report identifies the ship by name, call sign and IMO number, gives position, course and speed, states the type and quantity of any dangerous or polluting cargo, and declares any defect or limitation affecting navigation. The report goes to the relevant shore authority: the French maritime traffic services and the Italian Coast Guard maintain the watch on the designated VHF channel, with the two national centres coordinating the traffic picture across the maritime boundary that runs through the strait. The system gives the shore stations a continuous, identified picture of who is in the strait and what they are carrying, which supports both the surveillance of compliance with the recommendations and the response to a developing casualty.
The reporting overhead for a transiting ship is small, on the order of the time the bridge team spends preparing and transmitting the structured report and acknowledging the shore station, comparable to the overhead of the WETREP system in the Wadden Sea PSSA. What BONIFREP delivers in return is the data layer that makes the recommendatory measures effective: a shore controller who sees a laden tanker entering the strait without a pilot can query the ship, remind it of the recommendations, and stand ready to coordinate a response if the transit goes wrong. The combination of mandatory reporting with recommendatory pilotage and avoidance is the practical answer to the constraint that the strait cannot be closed.
The international-strait constraint under UNCLOS
The legal status of the Strait of Bonifacio is the single most important factor in understanding why its PSSA is built almost entirely on recommendations. The strait is a strait used for international navigation connecting two areas of exclusive economic zone or high seas, and under the United Nations Convention on the Law of the Sea of 10 December 1982 such straits are governed by the transit-passage regime of Part III, Articles 37 to 44. Transit passage is the right of all ships and aircraft to continuous and expeditious passage through the strait, and it is a stronger right than innocent passage: the coastal state cannot suspend it, and it cannot impose conditions that in practice deny or impair it.
Article 41 lets the states bordering a strait designate sea lanes and prescribe traffic separation schemes, but only when proposed to and adopted by the competent international organization, the IMO, and Article 42 lets them make laws on a closed list of subjects, including the safety of navigation, the regulation of traffic, and the prevention of pollution by giving effect to applicable international rules on the discharge of oil and oily wastes. Crucially, Article 42(2) provides that such laws shall not discriminate among foreign ships or have the practical effect of denying, hampering or impairing the right of transit passage. A compulsory-pilotage rule or a mandatory exclusion of foreign tankers would run into exactly that prohibition, which is why France and Italy framed the pilotage and avoidance measures as recommendations.
This is the same legal tension that surrounds the compulsory-pilotage measure in the Torres Strait, where Australia treats IMO-recommended pilotage as mandatory under its national law while some flag states regard pilotage in an international strait as recommendatory under the transit-passage regime. France and Italy chose not to provoke that dispute at Bonifacio: they accepted the recommendatory framing from the outset, and the PSSA resolution reflects that choice. The result is a PSSA whose protective force comes from the combination of a lawful mandatory reporting system, strongly worded recommendations recognized by the IMO, the coastal states’ own port-state and own-flag powers, and continuous shore surveillance, rather than from a binding exclusion of foreign ships.
The discharge dimension is different. UNCLOS Article 42 expressly allows strait states to give effect to applicable international discharge rules, and the whole Mediterranean is a MARPOL Special Area, so the oil and garbage discharge restrictions inside the strait are mandatory and enforceable in a way the navigational recommendations are not. A ship may have a recommendation-only obligation to take a pilot, but it has a binding obligation not to discharge oil or garbage in breach of the Mediterranean Special Area limits.
Relationship to the Mediterranean Special Area and the 2025 SECA
The Bonifacio PSSA sits inside a stack of MARPOL regimes that cover the whole Mediterranean, and keeping the layers straight matters for compliance. Under MARPOL Annex I, the Mediterranean Sea is an oil Special Area, which tightens the conditions on any discharge of oil or oily mixture from machinery spaces and effectively prohibits operational oil discharge from the cargo of an oil tanker inside the area. Under MARPOL Annex V, the Mediterranean is a garbage Special Area, which prohibits the discharge of garbage other than narrowly defined food wastes and cargo residues under strict conditions. A passenger-ship sewage Special Area under MARPOL Annex IV also applies to parts of the Mediterranean. These are mandatory discharge regimes, and they apply in the strait by virtue of covering the whole sea, independently of the PSSA.
The most recent layer is air emissions. From 1 May 2025 the entire Mediterranean Sea became a Sulphur Emission Control Area under MARPOL Annex VI, adopted by Resolution MEPC.361(79), capping the sulphur content of fuel oil used on board at 0.10 percent mass by mass, the same limit that already applied in the North Sea and Baltic ECAs. The Mediterranean SECA means a ship transiting the Strait of Bonifacio must burn fuel at or below 0.10 percent sulphur or operate an approved exhaust-gas-cleaning system, and must hold the bunker delivery notes and fuel-changeover records to prove it. The SECA is a Mediterranean-wide emission control area, not a Bonifacio-specific measure, but it bears directly on the strait’s air quality and on the local marine park.
The distinction practitioners must hold is that the PSSA, the Special Area and the SECA are three separate instruments with three separate legal bases. The PSSA addresses the navigational risk through recommendations and reporting. The MARPOL Special Areas address operational discharges. The SECA addresses fuel-oil sulphur. The PSSA does not impose any new discharge or fuel requirement of its own; it relies on the existing MARPOL framework for those and adds the navigational layer on top. A vessel inside the strait is concurrently subject to all three, plus the BONIFREP reporting and the broader Barcelona Convention regional-seas regime administered through the UNEP Mediterranean Action Plan.
Enforcement, surveillance and the practical compliance picture
The day-to-day administration of the PSSA falls to the French and Italian maritime authorities operating from shore stations on each side of the strait. The French side is covered by the regional maritime traffic surveillance organization and the prefecture maritime for the Mediterranean, and the Italian side by the Coast Guard, the Guardia Costiera, working under the maritime traffic services. The two share the traffic picture across the strait and run the BONIFREP watch jointly, because the maritime boundary between France and Italy runs through the middle of the channel and neither state alone has jurisdiction over the whole passage.
Enforcement against a foreign ship in transit is the limiting case. For a ship simply exercising transit passage, the coastal states’ powers are bounded by UNCLOS Article 42, so the response to a ship that declines the recommended pilot or transits the strait when it was recommended to avoid it is, in the first instance, a reminder and a record, not a detention. The force comes from the other directions: the port-state-control regime through the Paris Memorandum of Understanding for ships calling at French or Italian ports, the flag-state authority each state holds over its own ships, the discharge-enforcement powers under the MARPOL Special Area regime, and the documentary trail that BONIFREP creates and that becomes evidence in any casualty or pollution investigation.
The compliance picture in practice is better than the recommendatory framing might suggest. The large majority of laden tankers and gas carriers route around Sardinia or Corsica or take a pilot, because the consequence of a spill in the strait is severe and the operators, charterers and underwriters all price that risk. The residual concern is the smaller or less scrupulous operator, the ship that takes the shortcut without a pilot to save a few hours, and that is the population the shore surveillance and the reporting system are designed to catch and deter. The strait has avoided a major laden-tanker grounding since the protective measures matured, which the two states cite as evidence that the recommendation-plus-reporting model works for an international strait where a mandatory exclusion was never legally available.
Commercial impact and route economics
The commercial pull of the strait is the reason a recommendation, rather than a closed channel, is the policy in force, so the route economics are worth setting out. A ship moving between the western Mediterranean and the Tyrrhenian Sea, or between the western basin and the Italian west-coast ports, can either thread the Strait of Bonifacio or take the open water around the southern coast of Sardinia or, less commonly, around the northern coast of Corsica. The strait route is the geographically direct line, and the diversion around Sardinia adds distance and steaming time that a master weighs against the grounding-and-spill risk the PSSA documents.
For a typical merchant ship the diversion around the south of Sardinia adds in the order of tens of nautical miles to a western-Mediterranean transit, with the exact figure depending on the origin and destination ports. At a bulk-carrier or tanker service speed of 12 to 14 knots, a diversion of that order costs a few hours of additional steaming and a correspondingly modest quantity of fuel, the same general magnitude as the chemical-and-gas-tanker divergence in the Wadden Sea PSSA. For a laden crude or product tanker, the operator can model that cost directly against voyage economics using a voyage planning and routing workflow, and the calculation almost always favors the diversion once the spill-liability exposure is priced in. The marginal fuel and time cost of routing around Sardinia is small against the potential cost of a spill onto a Posidonia meadow inside an international marine park, where the cleanup, the civil-liability claim, the loss of hire and the reputational damage dwarf the few hours saved.
The pilotage element carries its own cost. A ship that follows the recommendation to take a pilot through the strait pays the pilotage fee and accepts the time for the pilot boarding and disembarking, against the reduction in grounding probability the local-knowledge pilot delivers. For a high-consequence laden tanker the pilotage fee is a rounding error against the cargo value and the spill exposure, which is why the practical compliance rate among large laden tankers is high even though the measure is recommendatory. The ferry operators running the year-round Corsica-Sardinia service know the strait intimately and operate it as routine, so the recommendations bear most heavily on the occasional transiting merchant ship without local familiarity, exactly the population that benefits most from a pilot and a report.
The leisure-craft surge in summer complicates the traffic picture without changing the cargo-risk calculus. The strait fills with charter yachts and motor cruisers in the high season, raising collision and grounding risk for small craft and adding to the surveillance load the shore stations carry, but the PSSA’s heavy-consequence measures target the bulk dangerous-cargo carriers rather than the leisure fleet. The two states manage the leisure pressure through the marine-park anchoring rules and seasonal restrictions in the reserve, a separate layer from the IMO PSSA measures, aimed at protecting the Posidonia meadows from anchor damage rather than at the spill risk the PSSA addresses.
Comparison with other PSSAs
Set against the other PSSAs, Bonifacio occupies a specific niche. The Galapagos PSSA rests on a binding Area To Be Avoided enforceable because the surrounding waters are not an international strait and Ecuador could secure a mandatory routing measure. The Wadden Sea PSSA rests on routing systems and the mandatory WETREP reporting that the three coastal states enforce inside their territorial seas. The Great Barrier Reef PSSA couples an ATBA with the contested compulsory-pilotage measure in the Torres Strait. Bonifacio, by contrast, is the PSSA where the international-strait status forced the protective measures down to recommendations plus the one lawful mandatory tool, ship reporting.
The closest legal analogue is therefore the Torres Strait, not because the geography matches but because both turn on whether a coastal state can compel pilotage in a strait used for international navigation. France and Italy avoided the Torres dispute by accepting the recommendatory framing at the outset, where Australia chose to legislate compulsory pilotage and accept the flag-state objections that followed. A practitioner planning a laden-tanker voyage through either strait should understand that the legal force of the pilotage expectation is genuinely different from a PSSA whose ATBA is binding, and that the prudent course (taking the pilot, or avoiding the strait) is the same regardless of the strict legal status, because the consequence of getting it wrong is what drives the insurance and liability exposure.
Within the Mediterranean, the natural comparison is the North-Western Mediterranean PSSA of 2023. Both are recommendatory PSSAs in waters where mandatory exclusion is constrained, both protect cetaceans linked to the PELAGOS sanctuary, and both rely on operator behavior rather than physical barriers. The difference is the dominant risk: Bonifacio guards against grounding and spill in a constricted strait, the north-western PSSA against ship strikes on whales in an open feeding ground, addressed through a recommendatory speed measure rather than a pilotage recommendation.
Limitations and practitioner notes
The PSSA designation creates no no-go zone and confers no power to stop a ship. A practitioner who reads “Particularly Sensitive Sea Area” as a closed area has misread the instrument. For a foreign ship in transit passage, the pilotage and avoidance elements are recommendations, and the only mandatory navigational obligation is the BONIFREP report. The binding obligations that do bite in the strait are the MARPOL Mediterranean Special Area discharge limits and, from 1 May 2025, the Mediterranean SECA 0.10 percent fuel-sulphur cap, and those flow from MARPOL, not from the PSSA.
Several pitfalls recur. The first is confusing the PSSA boundary with a routing prohibition: there is no IMO-adopted mandatory Area To Be Avoided here, unlike Galapagos, so a course line through the strait is not a per se breach of an IMO measure. The second is treating the Sardinian regional heavy-fuel-oil restriction as a uniform international rule: it is a regional or national measure with the same UNCLOS-transit limits on enforcement against a foreign ship in transit, and it must not be conflated with the Mediterranean-wide MARPOL SECA, which is the binding fuel-sulphur instrument. The third is overlooking BONIFREP: the reporting system applies from 300 gross tonnage and is mandatory, and a missed or defective report is the most likely detainable navigational defect a port-state-control officer would record for a ship calling after a strait transit.
The fourth pitfall is the assumption that taking the open route around Sardinia removes all PSSA-related obligations. The whole Mediterranean is a MARPOL Special Area and a SECA, so the discharge and fuel obligations follow the ship onto the open route; only the strait-specific navigational recommendations fall away. The fifth is underestimating the current and weather. The 2 to 4 knot currents and the Libeccio gusts are the physical reason the pilotage recommendation exists, and a passage plan that treats the strait as an 11 km open gap rather than a current-swept reef field misjudges the hazard the PSSA documents. A laden tanker master who declines the recommended pilot is operating inside the letter of the law and outside the spirit of the designation, and the casualty record the strait carries (from the Semillante onward) is the reason both states keep the recommendation in force.
Finally, the enforcement reality cuts both ways. The coastal states cannot detain a transiting foreign ship for declining a pilot, but they record it, and that record, the BONIFREP log and the shore surveillance track, becomes evidence in any pollution prosecution, civil-liability claim or P&I coverage dispute that follows a casualty. The recommendation is recommendatory in the moment and consequential after the fact.
See also
- Particularly Sensitive Sea Areas: IMO PSSA guide
- Particularly Sensitive Sea Area: Wadden Sea
- Particularly Sensitive Sea Area: Galapagos
- Particularly Sensitive Sea Area: Great Barrier Reef
- North-Western Mediterranean PSSA
- Mediterranean SECA 2025
- Emission control areas
- UNCLOS overview for shipping
- SOLAS Chapter V safety of navigation
- MARPOL Convention
- Barcelona Convention 1976
- Marine voyage planning and routing
- Canals and straits
- Calculator catalogue
References
The principal instruments are the IMO PSSA portal, Resolution MEPC.204(62) designating the Strait of Bonifacio PSSA on 15 July 2011, the Revised PSSA Guidelines of Resolution A.982(24) as amended by Resolution MEPC.267(68), the IMO ships routeing and ship reporting framework under SOLAS Chapter V, and the UNEP Mediterranean Action Plan administering the Barcelona Convention. Full citation links appear in the frontmatter.