Spot Trace (Uses satellite for both GPS and position uplink)
Gitterback (Ejects a bobber on a kevlar line when submersed in water)
Marco Polo (Uses 900 Mhz and direct transmitter/reciever)
Of course it depends on whether it is fresh or salt water, but at worst, I would expect to reuse the shell, legs, feet, etc. and of course get whatever footage I was shooting.. I have 4 spare motors waiting in the wings
Amazingly, several people here have dunked theres, dried them out, and flew them within days...