I would purchase the Garmin GPS 72. I purchased the GPS 76 last year and the 72 seems to be about the same product but costs less (although I have not compared every feature). It is made for marine navigation, as is the 76. It already has tons of waypoints programmed in and it is suppose to float. But you can buy one and let me know if passes the float test. I have not used the 76 all that much, but it seems to work very well.