A buddy of mine had a different method of getting his cooler into the ocean (same guy that almost lost his passenger last weekend.)
Monday in Monterey; most of the divers had gone home Sunday afternoon, so nobody on the ramp but Jeff. Jeff and Steve get gear ready and into the boat. Laughing joking, generally having fun.
Back the boat into the water, hit the brakes to break it loose... nothing. Back in a bit more, still nothing. Pull forwards a bit, get a running start backwards, hit the brakes, and everything in the back of the pickup slides out into the bay. A wooden tank rack, 2 cylinders, a large ice chest (which, of course, opened upon sliding out), assorted clothes, floats, and other dive gear.
The next 15 minutes or so are spent retrieving all the stuff, while trying not to fall over from laughing. Somehwere along the way, Jeff realizes he took off one transom tie-down, rather than two. Releasing the strap has the boat jump up about a foot, and the trailer dropping almost on his foot.
Not quite as spectacular as yours, Smokie, but probably a lot more entertaining. Too bad I had gone home (still a working stiff.)