Churaumi Aquarium is a world class aquarium located on the Motobu peninsula. Attractions include one of the world’s largest tanks with huge whale sharks and manta rays. The aquarium is located in Ocean Expo Park with a beautiful public facility called Emerald Beach.
The official site is at http://www.kaiyouhaku.com/en/
The better OCVB synopsis is at http://www.ocvb.or.jp/card/en/0120531201.html