Japan's diving highlights
Around February, ice floats from the Sea of Okhotsk start heading down towards Hokkaidō’s Shiretoko Peninsula (Hokkaidō Pref.), where it is possible for divers comfortable with drysuit diving to brave the cold and dive under these floating blocks of ice, usually between February to March
It is possible to dive kelp-forest environments in Japan, mainly in Hokkaidō (Shiretoko’s Rausu, or Hakodate’s Usujiri sites, for instance), and also, around Tōhoku’s Sado island (Niigata Pref.). in the spring months, usually from April to June.
The Chichi-jima area in the Ogasawara/Bonin Islands offers numerous WWII wrecks, including the Daibi-Maru (sometimes recorded as Daimi-Maru), lying at 33 m depth in Chichi-jima harbour.
These wrecks are not all easily accessible, and some require special equipment and adequate training, or permits, so do your research.
It is possible to dive a 120m cargo vessel lying broken in two pieces at around 30m in Atami (Shizuoka Pref), which acts as an artificial reef and attracts plenty of marine life.
It is possible to dive an purposedly sunk, largely intact 30m long tugboat, lying at 18m in Shirahama’s Edose area.
Hashira-jima, an island in the southern Hiroshima Bay, on the Seto Inland Sea, offers the chance to dive on a sunken battleship of the Japanese Navy, the Mutsu, a 224 metres long and 34 metres wide wreck sitting at a depth of 40 to 10 metres.
The Mutsu sank in June 1943, after one of her aft magazines accidentally detonated while she was at anchor.
Futaoi Island, also in Yamaguchi Prefecture, offers the chance to dive two purposely sunk wrecks, the Myoko Maru sitting at 24m, and the Rokuren Maru at 27m, which serve as healthy artificial reefs for the Kannon Strait’s marine life.
There is the option to do some wreck diving at multiple sites in the Kyūshū areas, including the Gotō islands (Nagasaki Pref.), which feature a 100m long shipwreck in the Shimogoto area, said to be one of the the largest in Japan.
Other sites, especially in the Satsunan islands offer great shipwrecks or sunken WW2 airplanes.
Yakushima island (Kagoshima Pref.) has a famous sunken Mitsubishi A6M Zero fighter plane for divers to explore at 20m (Zero-sen point, Isso).
Karatsu, in Saga Prefecture, is famous for its sometimes violent weather and currents, which led to many shipwrecks in the past.
Local cargo was mainly porcelain and chinaware, remainder of which are sometimes found on local dive sites.
Yoron island also has an purposely sunk wreck, lying at just over 30 m depth, often visited by schools of tuna and trevallies, along with a (slightly kitsch) Greek-style man-made structure.
The Okinawa region was the stage of fierce battles at the end of WWII, and there are many wrecks lying in its waters.
These wrecks are not all easily accessible, and some require special equipment and adequate training, and sometimes permits, so do your research in advance.
One of the most famous of these wrecks is the USS Emmons, resting close to coast of Okinawa’s Ko-uri island (also famous for its heart-shaped rocks…), roughly between 36 and 45 metres below the surface.
This 106 m long vessel was hit by five kamikaze (tokkōtai) suicide attack planes, and was deliberately sunk by the United-Statian crew, after heavy damage and loss of life.
Because of its depth, the USS Emmons wreck is an advanced dive, which ideally requires special training and experience (more than 50 deep dives) to be dived to the max recreational depth of 40m, and extra equipment to be explored efficiently beyond.
The USS Emmons wreck is also commemoratively dived by Japanese and American divers on the yearly anniversary of its sinking.
Remarkable Underwater Topography
Hokkaidō also offers possibilities to dive kelp-forest environments (in Shiretoko’s Rausu, or Hakodate’s Usujiri sites, for instance) and interesting caverns/caves.
The Kansai region’s topographical highlights include the Black Tunnel, an arch between two large rock formations, starting at 32 metres, also in Kushimoto (Advanced Open Water or equivalent certification / deep training required).
In Hyōgo Prefecture, the Takeno dive site offers the chance to dive a 25m wide and 15m high cave, with a 40m tunnel, that is only 5m wide at a point.
In Owase (Mie Pref.), a site called Gyosho consists of an artificial reef made concrete blocks placed on the sandy bottom. It’s become one of the most popular dive sites in the area, since the blocks attract a lot of life, and including seasonal migratory fish, local reef fish and macro critters.
The Oki islands are the remnants of an ancient volcano’s caldera, and offer really interesting topography, including Japan’s highest sea cliffs on land as well as underwater rocky pinnacles, arches and caves, and also leafy green seaweed bottoms, that offer shelter to smaller marine life, including seahorses.
The Kyūshū region offers great volcanic topography, notable around Kagoshima’s famous active volcano island, Sakurajima, which also offers dynamic underwater features, including a drop-off to 200m+, made by lava flows from recent eruptions.
Okinoshima (Fukuoka Pref.) along with many other Kyūshū dive sites offer exciting volcanic terrain underwater.
Kagoshima’s Bonotsu area is said to offer the best visibility in Kyūshū, with an average of 15m+, reaching 30m+ in the winter months.
Yoron Island, which has no rivers and is surrounded by very deep water, also generally offers great, 20 to 35m+ visibility and, along with dynamic volcanic terrain
The islands of the Okinawa region are primarily made of coral limestone or volcanic rock, and thus often present complex and interesting underwater topographical features.
Out of these, Miyako’s group of 6 islands is very famous in Japan for its coral limestone-based underwater environment, where rain and seawater erosion gave birth to a multitude of caverns and caves (especially in Irabu and Shimoji islands), tunnels and swim-throughs, canyons, boulders and arches, which make for fun exploration dives.
Miyako’s topographical highlights also the island’s famous “Blue Cave”, the “W-Arch”, the two-chambered “Maō No Kyūden”, the “Cross Hole”, where light shines through cracks in the rocks.
Another famous site is “Gakeshita”, where you can surface inside a large volcanic boulder, only to be surrounded by a misty vapour, formed by rising and falling water levels in this highly humid, closed-off environment. Equally famous is Tori-ike on Shimoji islands, two small ponds connected underwater, where you can experience the mysterious effects of chemoclines and thermoclines when swimming from one to the other.
Okinawa Main Island also has a famous “Blue Cave” at Cape Maeda, where incoming sunrays give the cave a distinct blue hue similar to Capri’s Blue Grotto in Italy, and is also famous for the Manza “Dreamhole“, which is a narrow vertical tunnel which you can follow towards the seabed, before turning 90 degrees and leading to the outside reef.
Ishigaki’s southern tip also hosts Japan’s largest coral lagoon, the “Sekisei Shōko” with coral bommies, sandy bottoms and caves (picture here)
THE YONAGUNI MONUMENT
In the Okinawa region, Yonaguni island’s “Monument” or Yonaguni Submarine Topography, is made up of massive monolithic rock formations of very fine sandstones and mudstones, that look somewhat man-made and have been the subject of passionate pseudo-archaeological speculation since their discovery in 1986 by Mr. Aratake, founder of the local Sou-Wes dive centre.
Whatever the truth behind the formations might be, they surely make for a unique, atmospheric exploratory dive, which might trigger your imagination, especially after with a little nitrogen build-up!
The Monument is found in relatively shallow waters, the bottom of the main structure sitting at about 25 metres, while the top is roughly at 5 metres.
However the Monument is still an advanced dive site, as it is generally swept by strong currents all year around.
Beyond the monument (and schooling hammerheads!), Yonaguni island is also famous for its topography, with plenty of caverns (including the Cavern of Light, “Hikari no Kyūden” site) and swim-throughs for divers to play around with, and excellent seasonal visibility
The islands of Kantō’s Nanpō archipelago (Izu islands, Ogasawara/Bonin islands) offer the chance to dive on healthy hard and soft coral reefs.
The Kansai area offers the possibility to dive hard and soft coral reefs, with large sponges, anemones, and interesting topography.
Wakayama Prefecture’s Kushimoto is famous for having one of the largest colonies of hard coral tables (Acroporidae) in Japan.
Many sites also offer beautiful soft coral colonies, such as Alcyonaceas, notably in Wakayama and Mie Prefectures.
Still in Wakayama Prefecture, Tanabe is well known for its deep-water colonies of bright yellow anemones, the Halcurias levis Uchida.
It is possible to see colonies of Alveopora japonica coral, a small zooxanthellate scleractinian coral species that occurs in shallow, non-reef habitats, in the area particularly in the Suō-Ōshima island chain on the Seto Inland Sea, (Yamaguchi Prefecture).
This coral is both endangered and rare, and only found in the north-western Pacific area including Taiwan, Korea’s Jeju Island and parts of Japan.
The islands of Uguru (Ugu), located 23 kilometers off the town of Sukumo, or Kashiwa are famous for their coral colonies, which are protected by the local government.
Sites like Tokushima Prefecture’s Mugi or Shishikuisho are famous for their colonies of hard and soft coral, including the Mugi’s “One Thousand years coral” (Porites lutea ), an impressive colony which now reaches a height of over 9 metres.
For adventurous coral enthusiasts, Kyūshū’s Tsushima island (Nagasaki Pref.), between the main islands of Japan and Korea in the Korea strait, is said to host the world’s most northern, cold water shallow coral reef in the world, made up of coral species discover in summer 1992.
The water there is generally cold, and diving activities have only just picked up, just like on the neighbouring island of Iki (Nagasaki Pref.), which also harbours such coral, along with good macro life and large schools of fish.
Coral-wise, the subtropical waters of Miyazaki Prefecture’s Nichinan is also famous for the beauty of its soft coral reefs, whereas the Nobeoka area is said to have one of Japan’s largest stony coral reef (Dendrophylliidae Gray)
The Okinawa region is famous for its healthy hard coral reefs full of life – especially in the Kerama (Zamami’s Chishi dive site for instance) or the Yaeyama islands. Miyako island is also famous for its staghorn and table coral (with over 100 reefs) and gorgonian seafans.
The islands of the central Okinawa area also have beautiful soft coral colonies and gorgonians, such as the Unanzaki area in the Kerama islands, or Sunabe Seawall on Okinawa Main Island, or the Ohama Sango site on the Chibishi Islands, just a 10 minute boat ride away from the main island, famous for its colonies of Porites lutea stony coral, where 10 metre wide bommies reach a height of up to 8 metres.
Ishigaki’s southern tip also hosts Japan’s largest coral lagoon, the “Sekisei Shōko” with coral bommies, sandy bottoms and caves (picture here)
Blue Waters and Excellent Visibility
Diving areas famous in Japan for their blue waters and excellent seasonal visibility include:
Hokkaidō’s Shakotan Blue [Shakotan Penincula, Hokkaidō Prefecture]
Western Izu Peninsula’s Ita Blue [Izu Peninsula, Shizuoka Prefecture]
The Nanpō archipelago’s Hachijō Blue [Izu islands, Tōkyō Metropolis] or the Bonin Blue of the Ogasawara islands [Ogasawara islands, Tōkyō Metropolis]
The central Sea of Japan’s Echizen Blue [Fukui Prefecture]
Wakayama’s Susami Blue [Susami Bay, Wakayama Prefecture]
Okinawa’s Kerama Blue [Kerama islands, Okinawa Prefecture] or Hateruma Blue [Yaeyama islands, Okinawa Prefecture]
In Shikoku, Uguru (Ugu) Island, located 23 kilometers off the town of Sukumo, or Kashiwa Island on the coast of south-western Shikoku offer amazing underwater visibility in season, which is said to be up to 50m on a good day, probably the best salt-water visibility in the country.
The Okinawa region is also generally famous for offering excellent seasonal visibility and clear blue waters, especially the Kerama Islands (Aka, Tokashiki and Zamami), famous for their Kerama Blue seas, or in the Yaeyama islands, especially Hateruma Island and its renowned year-round Hateruma Blue.
Endless Freshwater Visibility
Hokkaidō’s Lake Shikotsu (Hokkaidō Pref.) a caldera lake, is reputed to offer the clearest fresh water in Japan, with 25m+ as an average minimum, to near endless visibility.The lake does not freeze over in winter and can be dived all year round.
In Honshū’s Chūbu region, it is possibile to do some altitude freshwater diving in Lake Motosu, the westernmost of the Fuji Five Lakes, located in southern Yamanashi Prefecture, at an altitude of 900 metres.
Mikomoto Island’s hammerhead dives are primarily drift dives in strong current.
Good drift diving options are found Kagoshima’s Tanegashima Island, and in other areas in the Satsunan islands (especially around the Amami, Ōsumi and Tokara islands)
The Okinawa region offers solid drift dives options, especially at current swept site like Yonaguni, Miyako and Kume islands, or in some sites of the Kerama islands, where you’ll have chances of seeing bigger pelagics and predatory action.
This will most likely change in the future, but in most cases, unless one is already the member of some community, local support for technical diving is mosly non-existent in Japan.
There is, however, one major exception, near the deep water sites of Osezaki (Shizuoka Pref., Chūbu region, Honshū island).
In the Osezaki area, structures like Divezone are more supportive towards technical divers, and offers, on advance special booking, a larger range of onsite gas-filling options (nitrox, trimix, oxygen…), along with rental of doubles, and Sofnolime for rebreather divers, as well as aluminium tanks, handy for sidemount configurations.
Underwater Rehabilitation Efforts
TŌHOKU'S PACIFIC COAST
Tōhoku’s marine ecosystem has always been one of the primary resources of the area, which was severely hit by the earthquake and tsunami that struck Japan’s Pacific coast on March 11, 2011.
Ever since disaster struck, dedicated volunteer divers have been in the water to recover and remove debris, and also to rehabilitate the local environment (recycling tsunamis debris into physical structures to provide shelter for marine life such as abalone and scallops and also restart edible kelp cultivation (konbu).
You can read more about the activities of the Sanriku Volunteer Divers here.
An Underwater Aurora Borealis
KYŪSHŪ (Satsunan Islands)
Bioluminescent algae form an “underwater aurora borealis”, which is visible in season near Iōjima in Kyūshū’s Satsunan islands (Kagoshima Pref.).
This unique underwater phenomenon, which delights photographers, is best viewed in autumn, when the visibility is good and a powerful Kuroshio warm current brings the right nutrients and conditions.
Underwater hot springs
It is possible to dive at an underwater hot-spring at Shikine island (in the Izu Islands, 3-hour boat ride from Tōkyō), which is also sometimes visited by turtles.
Another underwater hot spring can be found at Hokkawa, in Shizuoka prefecture
Underwater Shintō shrine
There is an underwater shrine, said to be the only one in the world, at the Hasama Underwater Garden (Tateyama, Chiba Pref.)
Underwater mail box
An underwater mail box was setup in April 2016 on Okinawa main island’s 5 Sunabe No.1 dive site, in the Chatan area.
As elsewhere, divers can buy water-resistant postcards, write messages on them with an oil-based paint marker and post them in a postbox situated underwater.
The letters are collected from the postbox every few days, taken to the local post office.
Underwater hot springs
Taketomi island, in the Yaeyama island group, has a dive site with an underwater hot spring.
Mikimoto Pearl Island (not to be confused with Chūbu’s Mikomoto), in Mie Prefecture, is one of the first places where pearl aquaculture was developed, and offers the chance to see Ama professional female freedivers at work, and visit a dedicated museum
Ama freedivers used to be found almost everywhere in Japan, but now the main place to see the Ama freedivers still at work is the Toba / Ise-shima area, also in Mie Prefecture.
It is even possible to organise a freediving session with the divers.
More on the ama here.
Underwater mail box
An underwater mail box was also setup in in Wakayama Prefecture’s Susami Bay.
There as well, divers can buy water-resistant postcards from a local store, write messages on them with an oil-based paint marker and post them underwater in the red postbox.
A shop employee collects the postcards every few days, and takes them to the local post office to be mailed…
Liveaboard cruises in Japan?
NANSEI ISLANDS (Kyūshū/Okinawa)
Liveaboard diving is certainly not common in Japan, however there seems to be some movement around the Nansei Islands, with cruises offered around closely connected island groups in Okinawa (Kerama and Okinawa Main island, Yaeyama Islands) and also around southern Kyūshū’s Satsunan Islands.
A few dive cruises have been organised around the Nansei on Japan’s one and only tall ship, the Miraie, which is now in partnership with major diving agent STW / Divenavi. A recent exploratory diving cruise on the Miraie focused on the Yaeyama islands, for instance.
One operator Stingray Cruises, are organising boat trips and short liveaboard cruises around northern Kyūshū’s Genkai Sea and Saikai area (islands of Okinoshima, Iki islands, and Gotō islands), as well as south Kyūshū’s Satsunan Islands.
Their Satsunan Island operations, Tokara Discovery Cruises, offer 3, 4, 5 and 7 night exploratory cruises around the Tokara islands / Satsunan archipelago area, but for logistical reasons, this is probably still off-the-map for non-Japanese speakers.
This are semi-private cruises organised around Okinawan islands, aimed at select photographers and videographers and more.
Similarly, these cruises might be difficult for non-Japanese speakers to join at the moment, for practical reasons.
This trend may be under the influence of the current (2021) Covid-19 related restrictions on international travel, or might actually represent an interesting development for the future of the Japanese diving industry.