This is called the #pumpfoil. She is #pumpfoiling You pump up and down with your legs and that motion alone is all that is necessary to translate via a hydrofoil under the water surface (like a wing) to give you lift and forward motion You need good balance, endurance, and if you stop pumping you lose lift and sink rapidly EDIT: this is Alina Kornelli. See @bruno@federation.network 's comment below EDITEDIT: @alinakornelli@youtube.com