Here is an amphibious robot from SuperDroid Robots with WiFi that can navigate land and water easily. It floats and uses its wheels for propulsion through water. It has a rugged chassis, a 10X PTZ dome camera, and a spring mounted IR camera. You can control it through your PC.
The robot has a hand welded aluminum base, IG42 24VDC 78 RPM gear motors, Sabertooth dual 25A motor controller, and everything you need to get started. It has a max payload of 25 lbs.