At "Nix Castle," designed to reflect the atmosphere of historic Japanese castles, visitors embark on a journey through a whimsical world woven by diverse marine life.

Stepping into the castle framed by its striking red-brick walls, a massive 8-meter tower tank greets you. Modeled after tropical southern seas, colorful tropical fish swim elegantly inside while blue light paints ripples across the walls like a living artwork. In the Aqua Tunnel leading to the castle basement, Alaska pollocks and large sturgeons glide through a 300-ton cold-current tank. Further along in the 620-ton warm-current tank, sharks and rays dynamically circle overhead. Surrounded by swirling schools of horse mackerel and the subtle sound of water, you will enjoy a truly immersive experience.

Featuring one of Hokkaido's largest jellyfish displays, softly illuminated translucent jellies drift peacefully, offering a soothing moment of tranquility. During the year-round Penguin Parade, you can hear their adorable footsteps up close and feel the vibrant energy of the animals firsthand. The "Interactive Zone" features three touch pools where you can feel the smooth skin of rays and sharks in cool seawater or experience the unique sensation of Doctor Fish (Garra rufa) gently nibbling your hands, creating warm and unforgettable memories with the creatures.