I was listening to one of my regular podcasts, Diggnation, and in today's episode, they were talking about a recreational vehicle I had seen before, but forgot long ago. This thing is both dolphin and machine. According to the manufacturer's FAQ, their fastest model will travel up to 40 mph (64 km/h) above water and up to 20 mph (32 km/h) and 5 feet (1.5 meters) below the water. Check this out.