Two people were snorkeling from V1. Due to the strong current Operator dropped the two gentlemen off and drifted with them. When they had drifted over the area Operator would pick up the two individuals and start a new drift. They had done this a few times and it was time for Operator to pick up the two individuals. Operator idled over to the individuals. Victim swam to the back of the boat as it approached him. Operator had put the engine in neutral however the prop was still spinning and Victim had swam too close. The propeller struck Victim on the leg. The individuals hailed for Coast Guard. USCG Key West arrived on scene first and transported Victim back to their station to meet EMS. Victim was transported to Lower Keys Medical center.