Beach Water Polo is usually played in a small field, with 4 or 5 players each size, depending on the age and level the players. It is usually play with the "basketball rules", by which after a goal, the keeper will start the play immediately (no need to start in the middle of the field.)
This means a very fast pace and exciting play. It is an interesting format in itself, requiring fewer people to form a game. It is also a good supplement for regular training in standard size swimming pools.
For young players, one of the tubes can be taken away, to form a field that is 10m X 10m, making it more fun.