Check this thing out, it's a surfboard that runs on an engine. The problem is that while this guy looks relaxed, he doesn't seem to be having much fun. And surfing is all about having fun.
But I do think it could have worked out for fishing on a pond. I wouldn’t brave waves standing up like that, though.
An engine could be useful on a surfboard if the engine was very light-weight. It could help you speed up to catch a wave, assist with the paddle out, and you could give it a rev as you’re about to air. The extra air would be cool and the paddling easier, but we’d lose a lot of the exercise benefits we get from surfing.

Well this should be interesting …

Some mislead kid practicing skimboarding before a road trip down to South Padre. He thinks any second now, he’ll get bucked off.

After a heavy rain, this guy in Russia takes full advantage.
Checkout this really cool game where YOU get to be the shark and eat people.
Anything can surf with a big enough surfboard.