My husband and I both had massive knee injuries from being dumped in the Rapids, my husband fell square on his knee and scraped it a little and had to have bone chips removed afterwards orthoscopically. I was a bit worse off and have a permanent, puckered scar from a VERY deep, very large, chunk removed from my knee by scraping across the bottom of the Rapids (the wound was 1 inch deep at the deepest point, 4 inches wide and 2 inches high). I was very lucky that it was ONLY a flesh wound, that it never got infected, and that no muscles and tendons were involved. If I had not been a very strong, competitive swimmer earlier in my life, I very well could have drowned. So if you have mobility issues, are over 50 or in a wheelchair, I would NOT recommend the Rapids in any way, shape or form.