water polo, swimming game encompassing features of soccer, football, basketball, and hockey. The object of the game is to maneuver, by head, feet, or hand, a leather-covered ball 27 to 28 in. (about 70 cm) in circumference into net-enclosed goals at opposite ends of a pool 19 to 30 yd (17.37 to 27.43 m) long and at most 20 yd (18.29 m) wide. The two competing teams consist of seven players each, one of whom is the goalie. Only one hand may be used to advance the ball, which must be carried on the surface. Rough defensive techniques permitted include ducking, i.e., holding a player underwater.
Water polo was devised in England in the 1870s and became popular in the United States in the early 20th cent. It is played mainly by club teams, although it is also popular in collegiate competition. Water polo has been an men's Olympic event since 1900; women's water polo was first played at the games in 2000. A far rougher version of the game, played with a soft rubber ball in a larger pool and known as American or softball water polo, was formerly popular in the United States. However, its extreme violence brought it into disfavor, and today only the international or hardball game is played throughout the world.