Natatorium

This Association shall be known by the name, style and title of "The Natatorium and Institute for Scientific Instruction in the Improvement of the Physical Powers," and shall have for its object the attainment by scientific inquiry and investigation of the most desirable and beneficial mode of physical exercise, and by the scientific use of natatorial, orthopedic, gymnastic and such other physical exercise as may be prescribed by the By-Laws of this Association, to improve the health and physical condition of those who may avail themselves of the advantages of this Natatorium and Institution, in conformity with the terms of its By-Laws.

Source: wiktionary

[page 124] Although the five public natatoriums in Milwaukee now accommodate about 1,200,000 bathers per annum, they are capable of serving 400,000 more people a year than at present. […] [page 126] [O]ne of the best ways to reform an unruly gang is to get them to be devoted to a vigorous, manly man. There seems to be very little of this spirit in the present natatoriums. This is due in part to the swarms in which the boys come to the pool whenever it is open to them.

Source: wiktionary

Although the public does not pay an admission fee for the privilege of using natatoria facilities, the city charges ten cents for towels and soap, and ten cents for the rental of swimming trunks and bathing suits. In 1948 total revenues were $20,284 from this source for all natatoria.

Source: wiktionary

THE WAIKIKI NATATORIUM'S FIRST EVENT. An outdoor, oceanside pool was envisioned as part of the Waikiki War Memorial Park, which honored Hawaii's soldiers killed in World War I. […] In 1927 the facility opened and became known as the Waikiki Natatorium. The 40 × 110-yard Natatorium was the world's largest open-ocean swim stadium.

Source: wiktionary