First up is Scuba Chess.
Not that far removed from a normal game of chess except you play with lead weighted pieces and the time to complete the game is limited by the capacity of your air tank.
Then there is Aqua Chess - a more novel approach to the art of sports combining.
Both players stand in the water at one end of a swimming pool with a chess board on the edge. The first player makes their opening move then sets off down the pool. When they are exactly at the other end then their opponent makes a move and sets off swimming too. Player one has now returned to the board and has to make his second move – quickly – because if they are caught in the pool then they lose. Players win either by winning the chess match or by catching up with the other player in the pool. A game both physically and mentally exhausting. It is important that both players should be evenly matched swimmers to make the game as interesting as possible.