Open registry

An open registry is a ship register that admits vessels owned by foreign nationals on liberal terms, the formal mechanism behind a flag of convenience. The owner need have no genuine economic link to the flag state and gains low registration fees, light or zero tonnage tax, and freedom in crewing and manning rules. Panama, Liberia, and the Marshall Islands are the largest and together flag much of world tonnage. The model is lawful under UNCLOS, which leaves the genuine-link requirement undefined, and the quality check falls to port state control rather than the flag administration.