Marco POLO is a swimming pool game that is popular among children and adults alike. It is a tag-like game where one person is designated as 'Marco' and the other players must try to find them by calling out 'Marco'. The player who is 'it' must respond with 'POLO' and the other players must then try to locate them. The game can be played in a variety of ways, such as with teams or with a designated area for the players to hide. It is a fun and interactive way to enjoy the pool and can provide hours of entertainment.