At Okinawa Island’s northern tip, Hedo Point is only suitable for diving on the calmest of days, and then, the site can only be experienced by experienced divers. Hedo Dome is a dive that takes you right into the heart of Okinawa Island; it is located under the cliffs that lie north of Ginama along Highway 329. Despite its seemingly accessible location, it can only be reached by boat, as the entrance is located beneath 45 feet of water under the towering cliffs that separate water from land and sky. Ready for a thrill? Come along for a look at one of Japan’s best dive sites.
Diving Hedo Dome
Formed by an air pocket at the time when Okinawa was still rising up from the sea as a molten volcanic mass, Hedo Dome is accessed via a huge opening that leads straight into the darkness beyond the face of the cliff. As you move along the passageway, it narrows slightly to about 15 feet across before rising up and into the earth, where an enormous pillar reveals itself to be a joined stalactite stalagmite combination. Looking like an ancient column that holds the ceiling aloft, it looks like a giant petrified tree trunk.
After you pass the column, you can continue making your way up and through the passage, and as you do, you’ll notice that the water’s temperature is becoming cooler quite fast. You’re entering both a thermocline and a halocline, where the warm salt water is blending with the cool fresh water that enters the cave from above. Before you enter the halocline itself, you may be able to shine your light up into the water above you, where you will see it swirling in a strange visual effect that only happens in places where marked salinity changes occur.
Soon, you’ll find yourself in gin-clear fresh water, which is very cold; and you will notice yourself swimming among huge stalactites that hang down from both sides of the passageway. After a moment, you’ll be able to surface inside Hedo Dome itself. It is awe-inspiring, with its ceiling nearly 100 feet above the surface of the water, and crystalline stalactites small and large hanging from the ceiling. You’re inside a living cave, which is still being formed, and the air inside is so cold that you can see your breath. It is fine to breathe this air; though it is cold, it is fresh.
New research shows that the Hedo Dome may have been inhabited by humans at about the same time as the Yonaguni monument was above ground and possibly being crafted by the cavern’s neighbors. As the underwater stalactites and stalagmites stopped growing thousands of years ago, while the cave was still above water, and as they are large enough to be thousands of years old themselves, it is incredible to think about what may have once taken place inside this spectacular cave.
Once all photos have been taken, and cold starts to set in, it’s time to turn back, down through the thermocline into water that feels warm and welcoming, for a trip back through the tube and out into the suddenly bright world along the seawall. If you have time, your dive master may take you to a second underwater room, where stalagmites rise up from the floor like snow-covered trees; here, there is quite a bit of sediment, so be sure to use careful finning techniques.
Once outside the entrance, you’ll welcome the warmth of the sunlight that plays magically on the coral and seafans that wave in the current. Angelfish, Moorish idols, butterfly fish, and many other colorful creatures seem to welcome you back to a more familiar world.
Although there are fishermen who will take divers to the site, it is best to err on the side of safety, and dive with professionals. To enjoy Hedo Dome, you should be reasonably fit, and you should be certified to dive in an overhead environment. Plan in advance by contacting local dive operators, who can help you make the most of what is certain to be one of the most incredible dive vacations of a lifetime; in addition to the dome, there are many other wonderful sites around Okinawa that are just waiting to be enjoyed.