The Waikīkī Aquarium is an aquarium in Honolulu, Hawaii, United States. It was founded in 1904 and has been an institution of the University of Hawaiʻi at Mānoa since 1919. The aquarium is the second-oldest still-operating public aquarium in the United States, after the New York Aquarium. Built next to a living coral reef on the Waikīkī shoreline, the Waikīkī Aquarium is home to more than 3,500 organisms of 490 species of marine plants and animals.