Yeah, I was at my Family's cottage on the weekend and saw those on the lake. The previous week on the news they had a "Consumer Report" study where a number of people have died from exactly that. They're 'flying' then a gust of air violently throws them into the water, where upon impact bones can be broken. They had home footage of a couple of brothers in Edmonton and the exact same thing happened, if not higher and the brother on the tube broke some bones (I think a rib bone too) and was knocked unconscious.
Regardless of the incidents, they are pretty cool!🙂 But as mentioned when I was younger my family didn't have much money so we (brother, friends and I) would grab punctured inner tubes from one of the farm tractors, patch it, and float down the river to the General store with a 6-pack of Coca-Cola--later to be followed by beer😉