Miyakojima: Caves, Tunnels and Arches - Underwater Topography with a Difference
Miyakojima Island is the place to go for limestone and unique dive sites created by natural forces, seismic and volcanic activity. Diving here is a chance to explore another world with fascinating geographical features. The island is about 300km from the Okinawa mainland, with spectacular coral reefs, huge tunnels, rocks, arches and caves. A couple of ocean currents that pass north of the island bring with them a sea of nutrients, plankton and an array of fish, adding to an already-vibrant and fascinating underwater environment.
Most of the caves and arches are winding, horizontal or stepwise tunnels which open out into more sandy wide areas and smaller coral reefs. Some are as deep as 40m to 70m and some inner parts can be almost or totally dark. The seawater in the area has very low energy and the sediments found along the bottom are generally very fine. A lot of the main dive sites that offer this kind of environment are found along Irabuisland, one of the many islets around Miyakojima. One site here, Gakeshita, consists of a large rock surrounded by smaller ones that divers can meander through. The surfaces are covered in anemones that all shield varying kinds of clownfish while it's also possible to spot trumpet fish, shaded batfish, purple queens and peach fairy basslets. The abundant sea life is evident at all depth ranges, allowing divers to see plenty of variety. Because of the coral in the shallower depths, this site is good for getting a feel for two totally different environments - coral gardens and limestone.
Gakeshita is also home to one particular rock that can be swum through. The route allows the diver to surface into an extremely humid pitch-black dome. The swell from the open sea enters the dome and recedes, bringing with it a misty sheet of vapour that hovers over the water, surrounding the diver. This vapour is formed when the water level rises and falls in an area of high humidity. The ocean seen from inside the dome is a transparent blue and along with the vapour, forms an almost mystical scene.
Other points offer a range of caves and small cliffs. Some of the rocks are like monolithsand one in particular, at a dive site called The Cross Hole, has a dark entrance into a small tunnel. Once inside the route goes straight up, its impressive and dynamic shape offering a glimpse of interesting limestone formations and sea life. The cracks and crevices that intersperse the edge of the wall are worth paying attention to. White spotted pufferfish and yellow fin goatfish greet you as you arrive and a shoal of yellow spot emperor fish flits around here and there. The exit to the tunnel is shaped very slightly like a diamond and the sun shining through as you emerge is spectacular. Some areas contain small bits of dead coral, sand and bits of rock where it's possible to sit and look up at the sun streaming through the openings.
After diving in the deeper depths, it's worth taking time out to unwind at Wataguchi Garden, a site that's home to gardens of staghorn coral, gorgonian fans and table coral with hidden gems such as squat shrimps and nudibranchs. Rays emerge here and there, shaking off their sand camouflage and disappearing into the distance as divers pass by. With a maximum depth of about 12m, this is a very easy and relaxing experience that is perfect at the end of a long day. The dive consists of meandering through rocks and coral heads along a bottom of pure white sand. Visibility is usually good here but there can also be slight currents and divers should be aware of the implications of stirring up sediment with fins. Some of the rocks are quite spread out, so swim in between each and you never know what you might find - medium-sized puffer fish and black spotted puffer fish rest or gently swim in the shade of the corals.
Miyakojima's underwater topography makes it distinctly different from other sites in Japan. It is slightly far to travel to but worth it if you want to experience a volcanic landscape that adds to the mystique of your dives, as well as crystal clear blue water and white sandy beaches.