Wave-riding water sports:
Get as many friends together as you can and ask them to line up in single file along the inside edge of the pool with very little space between them. Tell everyone to swim slowly around the pool for a few minutes, then faster, then as fast as they can. The water will “carry” them around the pool after a while. It’s so cool!
This is like water polo with hoops instead of goals. Grab a ball and two hula-hoops. Place hoops on each side of the pool. Two teams play and no one is allowed to hold the ball for longer than five seconds.