I think snowmobiles have improved more than about any vehicle in the last 20 years. I remember in High School(late 80's) have a 440 and it was one of the fastest around. 20 years later they are twice as fast and a lot lighter.
Central Iowa is just too far south for snowmobiles and I hate towing. It's suprising how much better the riding is in Northern Iowa.
Nevertheless, it is quite common for people to race them on rivers in Alaska during the summer. But they are referred to as either snowmachines or sno-go's.
I had a Yamaha when I was in high school, and spent a lot of the winter riding on the river once it was frozen. I've crossed quite a bit of open water, but only about 10-15 yards at a time. I remember coming home for Christmas break my freshman year only to find that the parents sold my snowmobile while I was gone. I was a little more that upset...
Growing up in NW Iowa we used to "chute the tube" with our sleds all the time. Our lake had a spot that was kept unfrozen for aeration that was about 300 yards long. You'd get your sled up to about 75mph before hitting the open water and sail right across there. It was an amazing rush.
Of course I did see a couple of guys over the years who didn't have enough speed or power to make it across. Not only did they end up in the freezing cold water, but they also had to pay the cost for the towers and divers to go down and fish their sleds out. :biglaugh: