Adventure Point Tubing at Keystone Resort has conveyor belts to make walking up the hill easier. Sorry no one under 5 and you have to be over 42" tall. Sorry little guys. Night tubing only open when night skiing is open.
If you're vacationing at Keystone in the winter, *do not miss* the tubing hill on Dercum Mountain. It's hilarious. Multiple tubing lanes have half "walls" (almost) to keep you on track -- there's no free for all here. It's all very controlled and organized (and safe), when staff hurl you in your innertube down the steep hill.
For our first run, my son and I each sat in our own tube, but I grabbed onto his handles so we flew down together. He didn't love it; that was his only run and he was happy to warm up inside the yurt with a buddy.
However, my 9-year-old daughter couldn't get enough; she asked to be spun fast down the hill. My husband, too, loved the speed. I thought it was hysterical, but after five runs in the snow and cold, it was plenty for me. The runs I did take, while holding onto my husband's or daughter's tube, were *such* fun. (They went down at least 7 times in about 50 minutes.)
No need to schlep your tube up the hill; a covered magic carpet whisks you up. Disco music and a disco ball add to the festive atmosphere.
For adventurous kids, the experience is well worth the $29/hour fee. In 2009, there was enough snow that the tubing hill was open for part of the summer. Fun stuff!