Swimming pool

A Swimming pool is a tank filled with water that is provided for people to swim in. Swimming is a popular form of recreation and exercise, and is also considered a survival skill. Starfleet officers are required to be able to swim six lengths of a swimming pool. (TNG novel Metamorphosis).

Constitution class starships had a swimming pool, which would often be filled in the morning with people getting in laps prior to breakfast. (TOS novel Ghost-Walker). Refitted Constitution class vessels had a pool in the secondary hull. (TOS reference guide Mr. Scott's Guide to the Enterprise).

By the 24th century, on Starfleet vessels the holodeck was used to create a simulation of a swimming pool instead of having an actual pool on board the ship. Holodeck pools were considered to be much safer than regular pools in that if the computer detected that someone was starting to drown the water would disappear. (TNG novel Metamorphosis). Despite this, many people preferred swimming in a natural setting. When Deanna Troi remarked that she was looking forward to swimming on Pacifica, Data informed her that the holodeck was capable of recreating a swimming pool. Troi told him that it wasn't the same. (TNG episode Conspiracy).