Photos: Seagoing robot in action

Dave Fratantoni, an associate scientist at Woods Hole (left), and postdoctoral student Benjamin Hodges prepare to lower the glider into the waters off the coast of St. Thomas in December. Since its first mission that month, the glider has traveled between St. Thomas and St. Croix about 20 times.

The glider comes to the surface every so often to fix its position via GPS and to communicate via satellite to a shore lab.