A swimming pool, swimming bath, wading pool, or paddling pool is a structure designed to hold water to enable swimming or other leisure activities. Pools can be built into the ground (in-ground pools) or built above ground (as a freestanding construction or as part of a building or other larger structure), and are also a common feature aboard ocean-liners and cruise ships. In-ground pools are most commonly constructed from materials such as concrete, natural stone, metal, plastic, or fiberglass, and can be of a custom size and shape or built to a standardized size, the largest of which is the Olympic-size swimming pool.
Swimming pools became popular in Britain in the mid-19th century. As early as 1837, six indoor pools with diving boards existed in London, England. The Maidstone Swimming Club in Maidstone, Kent is believed to be the oldest surviving swimming club in Britain. It was formed in 1844, in response to concerns over drownings in the River Medway, especially since would-be rescuers would often drown because they themselves could not swim to safety. The club used to swim in the River Medway, and would hold races, diving competitions and water polo matches. The South East Gazette July 1844 reported an aquatic breakfast party: coffee and biscuits were served on a floating raft in the river. The coffee was kept hot over a fire; club members had to tread water and drink coffee at the same time. The last swimmers managed to overturn the raft, to the amusement of 150 spectators.