Riders rest on horses in front of the Cannon Beach Natatorium between 1926 and 1928.

Natatorium 

[næt•ə•tɔr•i•əm]

noun

plural, natatoria

1. arch. an indoor pool for swimming, esp. a free-standing building that houses an indoor swimming pool. The pool buildings that littered the Oregon Coast in the early 20th Century, from Nye Beach to Seaside, relied on pumping in heated seawater from the nearby Pacific Ocean, and offered concessions and entertainment, such as nickelodeons and live music

Origin:

First recorded in 1890 and arising in New England from the Late Latin verb, natāre (meaning “to swim”) + -atorium (a loaned suffix from Latin denoting a place). Natatorium literally means, “a place to swim.”

The term was at its height of popularity in the U.S. around the 1920s, just as many of the buildings along the Oregon Coast were being constructed. The term fell steeply out of fashion in the early 1960s, around the same time the last one on the North Coast, the Seaside Natatorium, closed.

“Cannon Beach’s natatorium was built in 1924 by William Mahon and was often referred to as ‘The Nat.’”

— Elaine Trucke, “Historic photos: Natatorium was more than a place to swim,” The Daily Astorian, Friday, March 27, 2015, P. 2C

“The building that now houses the aquarium opened as Seaside Baths, a natatorium, in August 1924, and it offered warm saltwater swimming.”

—Katherine Lacaze, “‘History and Hops’ educates with frosty pints of craft beer,” The Daily Astorian, Thursday, Nov. 12, 2015, P. 3A

“SEASIDE, Or., Oct. 18.—(Special.)—Work will be commenced about January 1 on a $30,000 natatorium in this city by J. E. Oates, who owns the site opposite the Moore Hotel.”

—“Natatorium is Planned,” The Morning Oregonian, Sunday, Oct. 19, 1913, P. 11