Okinawa Churaumi Aquarium

Stand still for a moment and listen. Beneath the voices of other visitors there is a low, steady hum, the sound of pumps moving sea water through the building day and night. The air smells faintly of salt. Outside, the light on the northern coast of Okinawa is strong and white, and the sea beyond the railings is a pale, clear blue. You are on the Motobu Peninsula, and the building in front of you holds a piece of that sea indoors.

The name comes from the Okinawan language. Chura means beautiful or pure, and umi means sea. So Churaumi is simply the beautiful sea. Locals use the word chura often, for a clear sky, a kind person, a well-made thing. It is a fitting name for a place that tries to show the waters around these islands as they really are, from the bright coral shallows down to the dark depths far offshore.

The aquarium sits inside Ocean Expo Park. The park grew out of the Okinawa International Ocean Exposition, a world fair held here in 1975, just a few years after Okinawa returned to Japanese administration. An earlier aquarium stood on this ground for decades. The present building opened in 2002, and it carried forward the research and the animal care of its predecessor. Much of what makes this place unusual today began in that older, smaller aquarium.

Notice how the visit is arranged. You enter near the top of the building and walk downward. This is deliberate. The route follows the path of light into the ocean. First come the shallow reef pools, open to the sky. Then the water grows deeper and the rooms grow darker, until you reach the deep sea. By the end, you have made a slow descent, without ever getting wet.

Near the start there is a shallow touch pool modelled on an Okinawan tide pool, the kind of rock flat that appears along the shore at low tide. Here you can see sea stars and sea cucumbers up close. Staff watch over the pool and explain how to touch the animals gently. Keep your hands wet and slow. These creatures live in the same kind of shallow water you can see from the park's own beaches.

Next comes a surprise most visitors walk past too quickly. The large coral tank is open to the sky above. Real sunlight falls on living coral, and fresh sea water is pumped in from the ocean outside. Because of this, the coral grows and spawns here much as it does on a natural reef. Look closely at the shapes. Some are branched like antlers, some are rounded like stone. All of them are alive.

Then the corridor bends, the light softens, and the wall in front of you becomes water. This is the Kuroshio Sea tank, named after the Kuroshio, the warm current that flows north past these islands from the tropics. The tank holds about 7,500 cubic metres of sea water. The window is a single great panel of acrylic, about 8 metres tall and more than 22 metres wide. It is around sixty centimetres thick, yet it looks as thin as glass.

The largest shapes moving past are whale sharks. They are fish, not whales, and they are the largest fish living in the sea today. They feed on tiny plankton and small fish, opening their wide flat mouths like a door. Watch how they swim, slowly, with almost no effort. Smaller fish often travel close beside them. In the open ocean, this habit gives the smaller fish shelter and the chance of scraps.

Now look for the wide, dark wings gliding through the upper water. These are manta rays. Here is a second surprise. In 1998, the earlier aquarium on this site recorded what is widely reported as the first birth of a manta ray in human care anywhere in the world. Since then, more mantas have been born here. Very little was known about how these animals reproduce, and much of that knowledge began in this park.

Keep walking downward and the rooms become darker still. Here the aquarium shows life from the deep waters around Okinawa, where sunlight does not reach. The animals look strange to us, with soft bodies, large eyes, and pale colours. Some of them glow. This part of the visit is quieter. Many people speed up here, but it rewards a slower pace. The deep sea covers most of our planet, and we have seen very little of it.

The aquarium is also a research centre. Its staff study sharks, rays, and sea turtles, and they work with scientists across Japan and beyond. Some animals arrive injured or stranded and are cared for in the park. This work is less visible than the great tank, but it explains why the animals here are kept in such careful conditions. You are watching a working scientific institution, not only a display.

When you step outside, the park continues. There is a free dolphin show in an open-air pool by the sea, a manatee house, and pools for sea turtles. Look out across the water. The island with a single steep peak is Iejima, a short distance offshore. Its rocky summit is easy to recognise from almost anywhere along this coast. A sandy beach lies within the park, a reminder that the real reef is only a few steps away.

Before you leave, stand at the railings and compare. Behind you is the great window, full of whale sharks and mantas. In front of you is the open sea, the same blue, the same current, moving north. The aquarium has never tried to replace that ocean. It brings a small part of it close enough to see. As you walk away, listen once more... the pumps, the wind, the waves on the shore.