Buoyancy Driven Glider

A buoyancy-driven glider is an underwater glider that moves by changing its volume rather than running a propeller. A pump shifts oil between an internal reservoir and an external bladder, alternating positive and negative buoyancy; fixed wings convert that vertical motion into forward glide along a sawtooth path. Slocum, Seaglider, and Spray gliders cover hundreds of kilometers over weeks to months at about 0.25 m/s, profiling CTD, oxygen, and optical data from the surface to 1000 m. Between dives the glider surfaces to fix GPS and relay data over Iridium. Low power draw gives the long endurance that a thruster-driven AUV cannot match.