The Osaka Aquarium Kaiyukan is an aquarium located in the ward of Minato in Osaka, Osaka Prefecture, Japan, near Osaka Bay. When it first opened, it was the largest public aquarium in the world. It is a member of the Japanese Association of Zoos and Aquariums, and the aquarium is accredited as a Museum-equivalent facilities by the Museum Act from Ministry of Education, Culture, Sports, Science and Technology.