Sharks and Minnows is a popular tag

Tag (game)

Tag is a playground game played worldwide that involves one or more players chasing other players in an attempt to tag or touch them, usually with their fingers. There are many variations...

 game played in swimming pools.

Rules

Generally Sharks and Minnows is played in the deep end of a large pool. The game starts out with one person selected as the shark and the rest as the minnows. The shark starts in the water on one side of the pool and typically shouts: "Minnows Over!", "Sharks and Minnows, one two three, fishies, fishies swim to me!", "Cross my ocean!", "All minnows come!", "Who wants to get eaten by a shark?", or some variant of such phrase, at which point the minnows may begin to dive in to swim to the opposing wall. If the shark manages to grab a minnow up to the surface, the minnow becomes a shark in the next round. After all the minnows have either reached the wall or been brought up to the surface, the shark(s) swim to the middle and the cycle starts again. If some of the minnows refuse to enter the pool, the shark may swim to the other wall and tag it after waiting a reasonable amount of time; whoever was still out of the pool when the shark tags the wall becomes a shark. The game is played until all of the minnows have been brought up to the surface, then the last person brought up becomes the shark who starts the next round.

The game is and/or was called "Sharks and Maidens" in some areas.

There are many variations and additions to these rules:

• Instead of tagging, sharks must hold some part of the minnow's body for three whole seconds before they become a shark.
• Drain base: minnows who are underwater on the pool's drains cannot be tagged out.
• No underwater tag: sharks can only tag minnows when some part of the minnow is above water.
• Pull up Shark: addition to rule of no tag underwater, the shark is allowed to force minnows to the surface of the water in order to tag them.
• While doing the "force minnows up to surface" version, the minnows can make a chain of linked arms. One will have to touch the opposite wall, and the other would have to touch a minnow that is about to get out.
• "No sharks charge": called by minnows while shark is saying "Sharks and Minnows...", prevents sharks from tagging wall.
• "All Minnows in": called by sharks immediately after "Sharks and Minnows..." before anyone calls "No sharks charge" to force all the minnows into the pool immediately.
• Depending on the size of the deep end, the amount used at the beginning when there is only one shark may be limited until he has tagged a certain number of people. This often helps increase turn-around in the game.
• The game can also be played on dry land with a soccer ball; a square is marked off with cones and all of the participants except one get a soccer ball. When a player with a ball, "the minnow," dribbles out of bounds or gets his or her ball kicked out of bounds by the player without the ball, "the shark," they are out. When only one person with a ball is left, he or she will be the shark for the next round.
• This game may also be played in the deep end of a swimming pool with a group of people in SCUBA gear who are the "minnows" and an equal size group of people in snorkel gear who are the "sharks." The minnows must stay in the deep end of the pool and the sharks must make the minnows surface (the equivalent of 'tagging' them) by ripping off their scuba gear or dragging them to the surface.
• In another form of this game the shark must make the minnows go under water using whatever force necessary to do so.
• Minnows can call "Early bird!" and jump in before the shark has called them across. Can be prevented by shark calling "No early birds!" at the start of the round.
• In one distinctive version, the minnows line up on one side of the pool, with the shark facing away from the pool on a perpendicular side. The shark's eyes must remain closed until at least one of the minnows has entered the water; if they turn around early they must take one step away from the edge. Rather than having multiple sharks, in this version the first person tagged becomes the next shark.

Lathering up with plenty of sunscreen can help make minnows slippery and evade the grasp of a shark.
Make sure a lifeguard is watching as this game can get intense and dangerous with older kids (12-20 yr old kids).

(Note: Other regions and countries may have substantially different rules.)