Waikiki Natatorium War Memorial, World War I memorial with saltwater pool in Waikiki, Hawaii, US.

The Waikiki Natatorium War Memorial is a commemorative site in Waikiki featuring a 100-meter saltwater pool built directly into the Pacific Ocean, decorated with Beaux-Arts architecture and stone eagles. The structure combines functional swimming facilities with monumental architectural design.

The memorial opened in 1927 to honor approximately 10,000 Hawaiian citizens who served in World War I, with 101 losing their lives. The project emerged from the desire to make these sacrifices and service permanently visible.

The memorial is not named after Duke Kahanamoku; it is a war memorial for the men and women of Hawaii who served in World War I. Kahanamoku, an Olympic gold medalist, made the first swim on August 24, 1927, his birthday. In the following meet, Johnny Weissmuller won the 100-, 400- and 800-meter events, and Buster Crabbe won the 1500 meters.

The memorial stands at the shore west of Kapiolani Park, at the end of Kalakaua Avenue. The pool closed in 1963, though it continued to be used afterward. Visitors can view the Beaux-Arts arch with its four stone eagles and the 100-by-40-meter saltwater basin from the surrounding grounds.

The opening ceremonies took place on August 24, 1927, which was Duke Kahanamoku's birthday; he made the first swim. In the meet that followed, Johnny Weissmuller won the 100-, 400- and 800-meter events, and local swimmer Buster Crabbe took the 1500 meters.