Aqua Planet Jeju, Public aquarium in Seongsan, South Korea.

Aqua Planet Jeju is a public aquarium in Seongsan, on the eastern side of Jeju Island, and one of the largest of its kind in South Korea. It is built around a central tank of considerable size, surrounded by multiple exhibition sections that display marine life from both local waters and distant oceans.

Aqua Planet Jeju opened in 2012 under the Hanwha group and is the largest public aquarium in South Korea. Its main tank, the Sea of Jeju, holds 5,300 m³. The facility later established South Korea's first specialized medical center for marine life. Two whale sharks and a manta ray were initially kept in the main tank; after one whale shark and the manta died, the remaining whale shark was tagged and released following criticism from animal rights groups.

The Ocean Arena hosts a dolphin and walrus show, with many performances hosted by an Eastern European synchronized swimming team. The aquarium also runs educational programs, including a diving experience in the main tank and ecological briefings on otters and penguins. From July 31, 2020, it held a Minions special exhibition for about a year.

The complex is divided into three halls — an aquarium, a marine science hall and the Ocean Arena — so plan your route around the show times at the arena. The main tank, the Sea of Jeju, holds 5,300 m3 and has a walk-through tunnel, which is the busiest stretch when tour groups pass. Educational sessions on otters and penguins and a diving experience in the main tank are booked separately, so arrange them before your visit.

Divers regularly enter the main tank during opening hours and swim alongside the fish while visitors watch through the glass. This means that on any given visit you may see a person moving through the water next to rays or sharks at close range.