High above Keystone's River Run, at the top of 11,640-foot Dercum Mountain, is Adventure Point, and it offers one of the most hair-raising, scream-inducing adventures you and your kids (42 inches and taller only) can have while sitting on your butts. Carved into the side of the steep mountain are five icy trenches reminiscent of a bobsled course, but much shorter, wider and straighter. For $29 per person, you get an inner tube and an hour to hit those trenches. Take the hill straight or have the attendant spin you; ride solo or attach yourself to up to three other tubers. Then take the moving walkway (basically an escalator) back to the top and do it again. And again.