The Chūbu region, close to neighbouring Kantō’s Tōkyō metropolis, offers great diving along the Pacific coast of Honshū.
The area is famous both for its awesome macro diving and iconic highlights such as Mikomoto islet dives with schooling hammerhead sharks.
The Chūbu region also offers diving on the Sea of Japan side (Chūbu’s Hokuriku area) , notably in Fukui, Ishikawa and Toyama Prefectures.
Both areas offer the occasional chance to see rare deep-water creatures.
On the Pacific coasts, the mountainous Izu Peninsula (Shizuoka Pref.), 1 to 2 hours south of Tōkyō, offers amazing macro, coral reefs, shipwrecks, and easy access to some of the nearby Izu Islands.
There are dive sites on both sides of the peninsula, which is renown for the variety of underwater environments and topography it has to offer, including steep drop-off, ancient lava flows, arches, canyons and caves (Hagachizaki, Shizuoka Pref.) sandy bottom areas for critters and stunning soft corals (Hokkawa, Shizuoka Pref.)
The Izu Peninsula includes the Izu Ocean Park (IOP) on the east coast, which offers excellent diving at roughly 100 km from Tōkyō, is one of the most popular diving areas in the Japan, along with the Ryū-Kyū /Okinawa area.
Diving areas, especially those offering easy access, will be definitely be busy in high season, particularly on week-ends and Japanese holidays, which visiting divers should try to avoid as much as possible – especially since normal weekdays are usually quite empty!
Let’s not forget the whole Izu Peninsula is also popular for both Tokyo and Nagoya tourists, not just for diving, but even more so for the hot springs resorts and beaches found in areas like Atami, Ito and Shimoda along the eastern coastline.
Cape Osezaki, on the west coast of the peninsula (from where you can sometimes see Mt Fuji), is another very famous and popular diving area, with possibly the best macro diving in Japan, facing Japan’s deepest bay, Suruga Bay, which plunges down to 2500 meters, increasing the chances of encountering rare deep-water creatures…
Do keep in mind that the tip of Cape Osezaki is only open on weekends and public holidays.
MAIN DIVING AREAS MENTIONED
- Izu Peninsula (Shizuoka Prefecture)
– Cape Osezaki, Osezaki, Suruga Bay
– Shimoda / Mikomoto Island
– Futo / Izu Ocean Park
Sea of Japan Coast
- Namerikawa (Toyama Prefecture)
- Rivers of landlocked Gifu Prefecture
- Lake Motosu (Yamanashi Prefecture)
DIVING HIGHLIGHTS AND ICONIC MARINE LIFE
SCHOOLING HAMMERHEAD SHARKS OF MIKOMOTO ISLAND
The Kuroshio warm current affects the southern part of the Izu Peninsula, and a the small island of Mikomoto (not to be confused with Mikimoto island in the Kansai region, famous for its cultured pearls).
Mikomoto Island is located roughly a 30-60 minute boat-ride away from the town of Shimoda at the western tip of the Izu Peninsula (Shizuoka Pref.), and is famous for the large schools of scalloped hammerhead sharks (Sphyrna lewini) that congregate in its waters, usually between the months of June and October, with July to September normally being peak “hammer season”.
This depends on water conditions, as the sharks are said to prefer warm water of above 20°C which is itself directly linked to the path of Kuroshio warm current, which flows very close to the island.
This also means that some hammerheads are actually be spotted all year round, including outside peak schooling season, and that there can also be unexpected surprises, such as other sharks including whale sharks (Rhincodon typus), oceanic black tip sharks (Carcharhinus limbatus) and sandbar sharks (Carcharhinus plumbeus).
Other interesting spottings include the odd mola-mola, dolphins or sailfish, as well as eagle rays and schooling pelagics such as amberjacks, tunas or trevallies, or turtles and carpet sharks, like angel sharks or the Japanese wobbegong (Orectolobus japonicus)
The main hammerhead dive (Zabu-ne) is a drift dive in strong current, often with rough surface conditions and the equivalent of an Advanced Open Water Certification / CMAS** + a minimum of 50 logged dives (bring your logbook!), with a last dive less than a year ago is required.
Check with your operator, but divers are usually required to have their own dive computer and a DSMB/Surface Marker Buoy/Safety Sausage, and dive time is usually limited to 35 minutes including the safety stop, or going to the safety-stop when a diver in the group reaches 70 bar remaining pressure, and maximum depth is 30m.
There is also a slightly easier dive (Kame-ne) where the current is lighter and it is possible to hang-on to the wall while watching the schooling hammerheads.
Diving the Mikomoto hammerhead sites can be quite pricey, but with the Ryū-Kyū’s Yonaguni Island (where the hammer season is in the winter months), Mikomoto is by far Japan’s most famous hammerhead viewing spot, and boats are usually full in season.
MACRO DIVING, ODD AND RARE CRITTERS
Like neighbouring Kantō, dive sites of the Chūbu region offer great macro diving (where you dive to find/photograph/film small rare critters), probably some of the best in the country (especially Osezaki in Shizuoka Pref., which is often considered to be one of the best macro diving areas in Japan).
Interesting critters you may encounter include:
A world class assortment of nudibranchs (sea-slugs), especially during the winter months in Osezaki (that has both sandy and mucky silty sea floors) and elsewhere around the Izu Peninsula.
There are many rare nudis and flatworms in these waters, and also less rare but highly popular/photogenic ones such as the “Pikachu”or “Shaun The Sheep” nudibranchs.
An experienced guide will sometimes spot more than 30 different types of nudibranchs in one single dive.
Seahorses and pigmy seahorses (Hippocampus bargibanti, h. colemani and h. pontohi).
Pipefish, pigmy pipefish and ornate and robust ghost pipefish (Solenostomus paradoxus and S. cyanopterus)
Rare and odd-looking frogfish/anglerfish (Antennariidae), especially in Osezaki (Shizuoka Pref.)
Rhinopias (!), leaf scorpion fish (Taenianotus triacanthus), seamoths (Pegasidae), devilfish (Inimicus) and other weird, photogenic critters
Various squid and pigmy squid, including the Bobtail squid (Sepiolida) octopuses and eels (ribbon eels, snake eels…)
Crabs, including spider crabs, decorator crabs
Rare shrimps, including the highly photogenic harlequin shrimp (Hymenocera picta) and imperial shrimp (Periclemenes imperator)
Rare, singular jellyfish and anemones
Rare blennies and gobies
Lumpfish, like the odd-looking Lethotremus awae, seen in winter
On the Sea of Japan side, Toyama Prefecture’s Namerikawa area also offers the chance to spot rarities such as the smooth lumpsucker (Aptocyclus ventricosus) in the cold January-February months, as well as iconic species such as the North Pacific giant octopus (Enteroctopus dofleini) up to mid summer, or the sex-changing Asian sheepshead wrasse (Semicossyphus reticulatus) especially in the Otomi and the Ishikawa area.
DEEP WATER CREATURES
Divers often encounter deep-water fish in the cape Osezaki / Suruga Bay area due to seasonal upwellings in the very deep waters of the bay (which plunge down to 2500m+).
The other major deep-water creature hotspot in the Chūbu region is Namerikawa in Toyama Prefecture, on the Sea of Japan side.
One of the famous deep-water creatures that show up seasonally in the Namerikawa is the snail fish, or Bikunin in Japanese (Liparis tessellatus) which rises up from depth of 200/300m, and delights divers with its cute features, soft skin and large comical eyes.
Another rare creature is the luminescent firefly squid (Watasenia scintillans) which comes to lay its eggs in shallower waters, and scintillates like an underwater firefly…
The Sea of Japan’s Namerikawa / Toyama bay area is not only famous for its bioluminescent firefly squid, it also recently started to offer the possibility to do black water diving, which is basically a tethered night dive in deep or open ocean, where divers simply hang out under the boat to see what creatures rise up from the depth.
More on Toyama Bay’s black water diving here.
MOLA-MOLAS AND EAGLE RAYS
Mola-molas (sunfish) can be seen seasonally, on various dive sites around the Izu peninsula (Shizuoka Pref.), especially at the Nakagi, Osezaki (which acts as a mola cleaning station) and also between April and August, at Futo.
The Numazu and Ita areas, west of the Izu Peninsula, are also popular for the variety of marine life that appear in early spring, including mola-molas, schooling eagle rays and the occasional manta ray.
The Atagawa and Arari areas are famous for their schools of Japanese eagle rays (Myliobatis tobiei) often spotted in the spring to summer months.
SCHOOLING FISH AND PELAGICS
Schooling fish and pelagics can be seen seasonally around diving areas of the Izu peninsula, especially on more exposed sites including the Mikomoto islet, Nakagi, Osezaki, Futo, Numazu, Ita, Atagawa and Arari.
OTHER MARINE LIFE HIGHLIGHTS
Izu Peninsula dive sites are also famous for Japanese bullhead shark (Heterodontus japonicus) and carpet sharks such as the Japanese angel shark (Squatina japonica) or the Japanese wobbegong (Orectolobus japonicus).
SPAWNING EVENTS AND AGGREGATIONS
Bigfin reef squid (Sepioteuthis lessoniana) spawning events can be observed seasonally, especially in the Futo dive site area on the east coast of the Izu Penisula, between June to August.
Chūbu’s landlocked Gifu Prefecture might not be the obvious choice for a dive trip, and yet it is one of the best places to observe Japan’s endemic giant salamander (Andrias japonicus), that grow up to an impressive size of 1.5 m.
The best place to see them is in the freezing (bring a drysuit!!!) mountain rivers of Gifu (and also in the Koza River, in the Kansai region’s Wakayama Prefecture), especially during breeding season, when the males are guarding the nests.
ALTITUDE LAKE DIVING
It is possibile to do some altitude freshwater diving in Lake Motosu, the westernmost of the Fuji Five Lakes (southern Yamanashi Prefecture), which is located at an altitude of 900 metres.
The lake has a surface area 4.7 km², and maximum depth of 121 metres.
TECH DIVING SUPPORT
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.
However, the deep water sites of Osezaki (Shizuoka Pref., Chūbu region, Honshū island), are an exception.
Local 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 and aluminium tanks, handy for sidemount configurations.
It is possible to dive a 120 m-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.
Click here for more precise, detailed and practical information on diving in the Chūbu region