There's a resort in Wisconsin Dells that I've been to quite a few times now, with an indoor wave pool. When we started going they had industrial clear inner tu

There's a resort in Wisconsin Dells that I've been to quite a few times now, with an indoor wave pool. When we started going they had industrial clear inner tubes that you could bring out into it; about half the people in the pool would have a tube. As you say the pool was nearly impossible to monitor as a parent from the sidelines, but there were lifeguards all the way around. Every once in a while they would stop the waves and jump in to pull somebody out - once it was even my own kid! They removed the tubes a couple of years ago. I was lucky as a kid, my parents kept sending me to swim lessons until I finally got it. I learned early how to do a side stroke, which is so relaxing you can keep it up all day.