Image 4 of 4 from Watercross racing: what to do with your snowmobile in summer

May 15, 2007 Here's an extreme sport that's been developing quietly behind our backs for 30 years now. Snowmobile fanatics around the world are lightly modifying their high-powered vehicles for frenzied "Watercross" races on lakes in the summertime. The massive machines buck, jump and wheelie their way to ferocious 60mph top speeds, and are as physical to ride and turn as a motocross bike. Game on!