The Wolfgansee is a beautiful lake surrounded by mountains and is a perfect setting to rent a boat or other type of watercraft. You can head down to the waterfront and rent a boat, but be sure to ask about proper licensing and other legal issues.
A major feature of summer recreation in St. Gilgen is hang-gliding. People take small gondola cars to the summit of one of the hilltops surrounding the town, jump off sheer rock cliffs, and then gradually drift down to the plains below. Did Yooperprof try out hang-gliding when he was here. Yeah, sure, you bet!