I got to ride as a passenger on one of these in Alaska - it was just a fluke meeting this guy and he offered me a ride. His was also enclosed - or had the seat up high, so very versatile. It had a Chevy 454, fuel injected, and counter-rotating dual props. Damn thing was fast as hell. He said it would do 60 in water, 80 on snow, and 100 on ice.

Looking at those things in the water, they don't appear to be the greatest boat. Then you realize they're not just boats.