Special Tactics Training Squadron students swim the length of the pool with their hands and feet bound during a pre-scuba class at Hurlburt Field, Fla., June 29, 2016. The training familiarizes trainees with the basics of water operations. The trainees perform tasks such as tying knots underwater, staying afloat without their arms and hands, and using snorkeling gear. (U.S. Air Force photo/Senior Airman Ryan Conroy)