Sinking the disk is a loss of possession

In water polo, the call from the referee is, "Ball Under." A player can not sink the ball. The same concept occurs with SKWIM. When a player sinks the disk, the opposing team gets possession of the disk. 

No Physical Contact with Opposing Players

Like the game of Ultimate, there is no physical contact among players. Guard the opponent close, but don't touch or grab the other player. 

When a player has the disk, another player can't grab the disk out of his or her hand. 

Hold the disk up to three seconds, not four