Marco Polo is a form of tag played in a swimming pool. It is a simple game that can be played with two or more players.
To play, One player is chosen as "It". That person closes his or her eyes, or is blindfolded, and counts to a certain number (usually 10 or 20). While the “it” person counts, the other players scatter around in the pool.
After counting to the pre-determined number, the “it” player tries to tag the other players, using only the sound of their voices to find them. The player who is "It" shouts out "Marco" and the other players must respond by shouting "Polo", which "It" uses to try to acoustically locate them.
When the “it” player tags another, that player becomes the “it” person and the game starts over again.
During the game, if "It" thinks that someone has climbed out of the pool, he or she can shout "fish out of water", and if anyone is out of the water they become "It". If someone sits on the side of the pool with their legs in the water, "It" can call out "mermaid on the rocks", or "fish out of water" and that player becomes "It".