Teledyne Brown Engineering, Inc., builds the Littoral Battlespace Sensing-Glider (LBS-G) for the U.S. Navy. The LBS-G is a long endurance UUV that is propelled by changes in buoyancy along with its wings and tail-fin steering. The gliders collect oceanographic data and can operate up to 30 days at a time on a lithium battery.
The U.S. Navy has demonstrated ocean gliders in a number of fleet exercises including RIMPAC 04, TASWEX 04, SMART SEARCH 05, TASWEX 05, RIMPAC 06, VALIANT SHIELD 07, and RIMPAC 08. They have been launched by T-AGS survey vessel, contract vessel, and via the Dry Deck Shelter on USS Buffalo (SSN 715).
An autonomous underwater Slocum glider similar to the Navy's LBS-G, "flies" by changing its buoyancy. The Slocum glider, conceived by Douglas Webb, was named after the first man to sail solo around the world.
See also:
Autonomous Submarine Drones: Cheap, Endless Patrolling
China's gliders: Haiyan & Sea Wing