GPS Devices - Underwater - Yes, Underwater

"Cool solutions for using GPS devices underwater"
CrunchGear (March 13, 2008)

"There's a pretty interesting MSN group made up of diving enthusiasts dedicated to using GPS devices while underwater."

If you're radio-savvy, you'll realize that the signals GPS devices use don't go through water, for practical purposes. These are working gizmos, though, with a low-tech solution.