You probably won't believe what I did today... I rode my bike in the lake near here! I stayed about 8 feet from the bank, but still, it was a blast! I was splashing water everywhere, climbing over the underwater rocks and terrain, and stayed cool that hot day. When I was riding, my handlebars were only about 2" above the water. At the final few runs around the bank, I was able to beep going for about a minute before the terrain got to me!
The only thing you really need to worry about is the crank bearings... they'll fill up with water and the water won't come out unless you take off your cranks. And it'll squeak after you water-cycle until you do let the water out.
I'm one of those guys who'll do anything if it doesn't scare the s out of me. I play now, fix later