I have an old video where they do it. It’s either “Crusty Demons of Dirt 2” or MotoXXX. I can’t remember which. Basically they go wide open 5th (250cc 2 strokes) on a beach with an almost flat taper into the water. When they hit the water, they skim accross just like snowmobiles do. The water sucks a lot of power because you can hear the bikes slowing down, they barely make it accross. The start at about 65-70mph, and end up going probably 300 feet accross to the other side.