Wing surfing
Kitesurfing?
Windsurfing?
Looks like.
A cross between the two.
Never seen this before.
Quick Google.
Turns out theyre probably.
Wing surfing.

“From a ground-up perspective, anyone who’s competent on a paddleboard could pick this up with basic instruction. You can also rig it exceptionally easily from the back of a yacht (where kites can be downright mischievous).