Today i just played this game with my group that they really enjoyed...its called The Underwater Game.
First you pick three campers to be the sharks, they stand in the middle of the court.
The rest of the kids have the run to the other side without getting tagged by the sharks.
If they get tagged they become seaweed, and can only move their arms, not their legs. They can also tag people as seaweed.
The last three kids are the next three sharks! We played 3 rounds before they had enough of it!