Competitive swimming is built on two course lengths. Long-course pools measure 50 metres and are used at the Olympic Games and World Championships; short-course pools measure 25 metres, or 25 yards in the United States. World Aquatics, the international governing body, specifies lane widths of 2.5 metres and minimum water depths for racing starts.
Outside competition, dimensions follow purpose. Diving wells reach 4.5 to 5 metres beneath high platforms, teaching pools stay around 0.9 to 1.2 metres so beginners can stand, and leisure pools vary depth along their length. Many municipal facilities combine these roles in one basin, separating a shallow learner zone from deeper lap lanes with a rope or a graduated floor.