Me and my wife have a patent on a man made one of those using a pump to recirculate the water down a ramp like that. We figured you could insert it into a pool or lake and have a hole. We were even thinking you could have two side by side for duel competitions like they have with skiing. It's pretty costly so we figured there wasn't much of a profit with making the thing. We were sort of thinking it would be cool to sell to YMCA's and stuff for the winter time.