A Floating Attraction in Amakusa
The Sea Donut Aquarium is one of only two floating aquariums in Japan — and the only one in western Japan. Situated on Maejima Island in Kami-Amakusa, the aquarium is immediately recognizable by its unusual circular silhouette bobbing on the Amakusa Sea.
The facility is organized into multiple sections, each named after a different continent, allowing visitors to observe marine life from various regions. What makes it especially unique is that, as a floating structure, visitors can peer directly into the surrounding sea through underwater windows and observe fish in their natural habitat.
Beyond the fish exhibits, the aquarium also offers a range of hands-on activities: visitors can feed tortoises and sea bream, join guided tours and even sign up for a one-day zookeeper program.
The biggest draw, however, is undoubtedly the dolphin experience. Dolphin encounters are especially popular, with options ranging from a trainer experience that mimics being part of a dolphin show to wading into shallow waters for the “Fureai Beach” dolphin interaction program. Note that these experiences require fees beyond the general admission ticket.
The aquarium sits within the larger Amakusa Pearl Garden complex, which also features restaurants, souvenir shops and a stylish seaside cafe.
Best Times To Visit Sea Donut Aquarium
The aquarium is open year-round, but visiting during the warmer months means longer opening hours and access to outdoor dolphin interaction programs. Every Saturday from April through December, the aquarium offers a special nighttime flashlight tour where guests explore the exhibits after dark. A particular highlight is the sea firefly, a bioluminescent creature that only lights up at night.
Weekends and Japanese public holidays (particularly Golden Week in late April to early May) can draw large crowds. Arriving early on weekends is advisable in order to secure a parking spot, as the lots can fill up quickly. Weekday visits in spring or autumn offer the most relaxed experience with pleasant weather and manageable crowds.