Sea Day, also known as Marine Day or Ocean Day, is the only Japanese national holiday in July and falls on the 20th this year. Originally meant to commemorate the return of the Meiji emperor to the Yokohama Port, it now marks the end of the rainy season—well, roughly. For those of us who live further from the bay, or who don’t fancy getting sand in our shoes on the beach, there are still ways to celebrate Sea Day without actually going to the coast. Japan boasts several aquariums where visitors can experience the beauty and diversity of marine life. Below are some of our top picks for the best aquariums in Japan.

Okinawa Churaumi Aquarium

The Shark Research Lab at Okinawa Churaumi Aquarium presents the world’s first exhibit of a captive-bred tiger shark. Their shark tank also houses other rare breeds, such as the silvertip shark and the silky shark, which can be seen nowhere else in mainland Japan. The largest tank, Kuroshio Ocean, offers a mesmerizing view of over 16,000 fish and 70 species. For 2026, the aquarium spotlights marine research with a new deep-sea shark exhibit featuring a rare embryo display developed through advanced breeding techniques.

Hours: 8:30 am – 6:30 pm (last admission at 5:30 pm)
Tickets: ¥2,180 for adults, between ¥710 – ¥1,440 for students, free for children under six (discounts for groups of more than 20)
Location: 424 Ishikawa, Motobu-chō, Kunigami City, Okinawa
Website: churaumi.okinawa

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Sunshine Aquarium

High above Ikebukuro, Sunshine Aquarium pairs skyline views with immersive marine displays. In 2026, it dives into the abyss with a special deep-sea creatures exhibition showcasing rarely seen species and interactive learning zones that explore life in extreme ocean environments. The rooftop Marine Garden remains a standout, where penguins appear to “fly” against the Tokyo skyline. Visitors can watch the penguins, otters, pelicans and dorados feed, as well as performances from divers and sea lions. Animal handlers conduct guided expeditions for an even more personal experience with the creatures.

Hours: 10 am – 7 pm Weekdays, 9:30 am to 8 pm Weekends (Spring & Summer), 10 am – 6 pm Weekdays, 9:30 am to 6 pm Weekends (Fall & Winter)
Tickets: Prices vary depending on the day
Location: Rooftop of World Import Mart Building, Sunshine City, 3-1 Higashi-Ikebukuro, Toshima-ku
Station: Ikebukuro
Website: sunshinecity.jp/en

Art Aquarium

During the Edo period, the kingyo (goldfish) became a prominent part of Japanese culture. At Art Aquarium in Ginza, goldfish become part of an immersive art experience inspired by traditional Japanese aesthetics. For 2026, the museum introduces its first collaborative installations with artists from different creative fields. A striking bamboo-and-acrylic spiral sculpture anchors the gallery, its flowing curves echoing the movement of the goldfish. At the same time, renowned flower artist Shogo Kariyazaki fills the space with dramatic floral arrangements suspended overhead.

Hours: 10 am – 7 pm
Tickets: From ¥2,200 – ¥2,700 for junior high school students and above, free admission for up to two children (elementary school age or younger) per adult
Location: Mitsukoshi Ginza Terrace, 4-6-16 Ginza, Chuo-ku
Website: artaquarium.jp

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Port of Nagoya Aquarium

The first step to protecting the ocean is to learn about it. In order to introduce visitors to marine marvels, the Port of Nagoya Public Aquarium displays creatures from all over the world, including the seas around Japan, tropical oceans, Australian freshwater bodies and even the Antarctic ecosystem. The North Building pays homage to cetaceans like orca whales and dolphins, animals that have adapted exceptionally well to underwater life over billions of years. The aquarium conducts talks with divers and penguin-keepers, training sessions for belugas and orcas and performances from dolphins.

Hours: Generally open from 9:30 am – 5:00 pm, hours may vary depending on the day
Tickets: ¥2,030 for adults (including high school students), ¥1,010 for junior high and elementary school students, ¥500 for children aged 4+ years (prices may vary depending on the season)
Location: 1-3 Minato-machi, Minato-ku, Nagoya
Website: nagoyaaqua.jp/en

Toba Aquarium

Toba Aquarium is famous for being the only place in East Asia where you can see a dugong in captivity. Aside from meeting this endearingly chubby marine mammal named Serena, visitors can sit and take selfies with walruses, watch seals and finless porpoises and see otters at feeding time. There’s also a stunning, large coral reef aquarium tank with a glass roof. Here, visitors can admire turtles and tropical fish drifting and darting above their heads and between the live coral. On the creepier side of things, delve into the deep sea in the Unusual Creatures Laboratory to see alien-like giant isopods and the bizarre, glass-like spiny lobsters.

Hours: 9:30 am – 5 pm
Tickets: Adults ¥2,800, children between ¥800 – ¥1,600 (free for children under 3)
Location: Toba 3-3-6, Toba-ku, Mie
Website: tobaaquarium.co.jp/en

Sumida Aquarium

On the fifth and sixth floors of Tokyo Solamachi are over 10,000 sea creatures. The Sumida Aquarium uses an artificial seawater production system, maintaining water quality and decreasing carbon emissions that are caused by transporting seawater inland. Visitors can wander around freely, chat with aquarium staff and even witness interactions between the animal-keepers and aquatic life. Sumida features an open indoor tank with penguins and fur seals, a magnificent jellyfish display and a research laboratory. They also recently introduced baby penguins to the pool.

Hours: Opening hours vary depending on dates
Tickets: Adults ¥2,500, high school students ¥1,800, junior high and elementary school students ¥1,200, children ¥800 (free for children under 3)
Location: 5-6F, Tokyo Skytree Town Solamachi,1-2, Oshiage 1-chome, Sumida-ku
Website: sumida-aquarium.com/en

Maxell Aqua Park Shinagawa

Equal parts educational display and show space, Maxell Aqua Park Shinagawa combines light and video shows with tanks of marine animals. Jellyfish Ramble is one of the park’s 11 zones, with a relaxing jellyfish display and immersive music. In spring 2026, it stages “SAKURA AQUARIUM,” a seasonal production that layers cherry blossom visuals, digital effects and synchronized dolphin performances into a full sensory spectacle.

Hours: Opening hours vary, but always open 10 am – 8 pm
Tickets: ¥2,800 for adults (including high school students), ¥1,300 for junior high and elementary school students, ¥800 for children and free for children under 4
Location: 4-10-30 Takanawa, Minato-ku
Website: maxell-aqua-park.jp/en

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Are you looking for outdoor activities to celebrate Sea Day? Read our guides to Mikuni Minato: A Peaceful Port Town Away from the Crowds, or Tokyo Day Trip: Enoshima Caves, Shrines and Sea Views.

This article was originally published on July 2, 2025, and updated by the Metropolis Japan team on March 4, 2026.