If you want to go under the sea, this Parallax Submersible ROV project by Richard will allow you to go where most electronics don’t want to go. With a goal of looking at the bottom of a lake in Michigan and watching some fish I think this project will do very well.

"This ROV is tethered to the surface with a 6 conductor Ethernet cable and nylon support line. It will be placed over the side of my boat and allowed to sink (buoyancy is adjustable with steel plates attached to the bottom of the main tube). Initially the tethered line is only 50 feet long.. Using the surface control console I am able to adjust left and right motor speeds forward and reverse (400 size electric RC brushed motors geared 6:1 and 3” diameter propellers cut down from electric RC props). Keeping the ROV fairly close to the boat I will be able to move it forward, backward and rotate it side to side. The control console has a 7” LCD monitor receiving signals from the TV camera mounted at the front of the main tube and viewing through ¼” polycarbonate plate. I have two 50 watt Halogen lights mounted on the forward top of the tube. I can control the intensity of the lights with a rheostat mounted in the surface control console. The lights are homemade using outdoor garden bulbs housed in 2” PVC with a polycarbonate plate lens."