Water polo is a team water sport. The game consists of four quarters in which the two teams attempt to score goals by throwing the ball into their opponent's goal. The team with the most goals at the end of the game wins the match. A team consists of 6 field players and one goalkeeper in the water at any one time. Except for the goalkeeper, players participate in both offensive and defensive roles. In addition to this, teams may have substitute field players and substitute goalkeepers who are not in the water. Water polo is typically played in an all-deep pool 7 feet deep and players require stamina and endurance to play the game.