This is the subwing.
It lets you “fly” underwater. The user hangs onto the carbon fiber wing as it’s towed behind a boat. A swivel allows you to control your movement. You can glide by coral reefs… swim alongside schools of fish… And maybe even play with dolphins. Norwegian Simon Sivertsen came up with the idea in 2010, when he was just 18. It’s kind of like underwater waterskiing.
But be careful- Sivertsen says not to go over 4 knots.