Our family went to the Wisconsin Dells this summer and stayed at the fabulous Kalahari Resort. The Resort boasts one of the country's largest indoor waterparks, including the attraction featured in the video. The Surfari is a plastic slope with water RUSHING upward, so the "rider" can kneeboard (or surf when they remove the divider). This video depicts my husband's (Timmy's) first attempt.
P.S. He did get better!