In one sentence, describe what the following article is about:

Choose a player to be the Shark. This player is now “it” and stands in the center of the pool (the “ocean”).  When playing with a lot of people in a large area, you can play with more than one Shark. 10 Minnows to 1 Shark is a good ratio. If many people want to be the Shark you can decide by flipping a coin, or playing rock, paper, scissors. Everyone who isn't a Shark is a Minnow. Minnows form a line at one end of the pool deck, facing the Shark. There should be at least twice as many Minnows as Sharks. To start, the Shark yells, "fishy, fishy, cross my ocean", or some variation of that. When the Minnows hear this call, they jump into the pool and start to make their way to the opposite end. The Shark must remain in place above water until the next call. Experienced swimmers can challenge themselves by requiring players to dive,  cannonball, or can-opener into the pool.
Pick a Shark. Have many Minnows. Start the game.