JAPANESE WATERS ARE PERHAPS better known for spawning sushi, tsunamis and Godzilla than for their rich diversity of marine creatures.
The country spans a huge latitudinal range, from the tropical south where coral reefs dominate, into the almost sub-Arctic north.
As a result, its biological diversity is great, with many different habitats accommodating a wide array of species.
Japan’s diving isn’t especially accessible for foreigners, but it’s well worth the effort.
I decided to visit a couple of the better-known spots, as well as visiting some places foreigners rarely, if ever, I was searching for a very special quarry.
Japan had been on my dive bucket-list for many years, and when Okinawa was announced as the location for the quadrennial Indo-Pacific Fish Biologists Conference, I jumped at the chance to attend.
I was ostensibly in Japan to present some of my pygmy seahorse research at the conference, but my actual goal was to find the elusive and undescribed Japanese pygmy seahorse.
There are hardly any images of these tiny fish and, like much of Japan’s marine life, it is barely known outside the country.
After months of online research (thank heavens for Google Translate) and detective work I narrowed my search to a couple of locations. Having spent years studying pygmies, I knew that finding these miniature fish wouldn’t be easy.
I had managed to fit in a few dives in Okinawa, but because it is closer to the Philippines than Tokyo it is heavily dominated by widespread tropical reef creatures rather than by endemic Japanese species.
My research indicated that the Japanese pygmy, or japapigu as it is known locally, isn’t found this far south. So after the conference I was keen to explore parts of Japan where fewer international tourists visit and the indigenous species are more apparent, and headed northwards to cooler climes.
That so many marine creatures in Japan are found nowhere else is down to local oceanographic conditions. The South Pacific Ocean gyre (large system of rotating ocean currents) pushes water in a counter-clockwise motion to become the East Australian Current (the one that carried Nemo from the Great Barrier Reef down to Sydney).
Similarly the North Pacific gyre, as the Kuroshio Current, pushes water from the Equator northwards to Japan. This is the Pacific’s largest current. It has a significant impact on marine eco-systems, taking warm water and tropical fish where you might not expect them.
This northerly flow also creates a barrier to fish trying to migrate south, effectively isolating them in Japanese waters, much like the giant tortoises, marine iguanas and Darwin’s finches of the Galapagos. In isolation, they have evolved into unique forms.

AFTER A FEW DAYS IN TOKYO I met Shingo of Kiki Diving Club. We drove south for three hours to the Izu peninsula. After clearing the urban sprawl the lush forests of Izu were a welcome relief.
Through Shingo, I had arranged a little tour of the sites around the peninsula, starting at Arari on the west coast. Like many of Izu’s sites, this was an unusual example of temperate muck-diving.
We tend to think of this as an exclusively tropical pursuit in locations such as Lembeh, Anilao and Milne Bay, but some cooler-water sites can be equally rewarding.
Over three dives at Arari I saw nine different frogfish of several species, amazing blennies, many dragon morays plus an array of other Japanese specialties. Despite appearing to have perfect environmental conditions there was no sign of the japapigu, but I did see a couple of endemic Shiho’s seahorses adorned with beautiful filamentous appendages.
The next day we headed north along Izu’s west coast to Osezaki, where views of Mount Fuji dominate the landscape. This is one of the area’s most popular sites and receives hundreds of visitors from Tokyo at weekends, so it’s worth visiting during the week if possible.
One of the attractive features of Osezaki is the very sheltered bay that allows diving even when rough weather renders the rest of the peninsula undiveable. Outside the bay we had some equally great dives.
Nutrient-rich cool upwellings, at around 19°C when I was there, bathe the area and encourage plankton growth and green water, which at first looked quite uninviting.
However, once down to around 25m an eerie forest of whip corals emerged and a thermocline brought with it clear water.
Here, an unusual assemblage of fish including Japanese cherry anthias, striped anthias and goldribbon soapfish were all first-time encounters for me, because they usually prefer much deeper water.

THE FINAL STOP on my Izu safari was also its best-known. Izu Oceanic Park (IOP) on the peninsula’s east coast is a long-established marine-protected area well set up for divers.
To cope with the weekend hordes, everything is run with outstanding Japanese efficiency. There are designated exit and entry routes from shore, a small mirror to check for hair in your mask, and even a shelf for leaving your glasses!
There are well-kept showers, toilets, a hot onsen bath, camera dunk-tanks, large areas for gear preparation and relaxing classical music played as you gear up. It was all very surreal, but very Japanese.
The small on-site shop has regularly updated maps with the location of animals in the area. We went from one rock to another to see the current resident seahorses, frogfish and tube blennies.
But despite having been recorded from the IOP, Japanese pygmies were nowhere to be seen. The shop staff had seen none for a while, so after a week exploring Izu my eggs were all now in the proverbial basket of Hachijo Island, my next stop.
I made the 40-minute flight from Tokyo to the island, 200 miles due south. The sub-tropical waters, heavily influenced by the Kuroshio Current, boast a plethora of rare and indigenous species, but I was getting nervous about my pygmy search.
Luckily I had the eagle eyes of Tanaka-san and Ogino-san from Concolor Diving with me. Within 10 minutes of the first dive they had found a pair of pygmies on the side of a huge algae-covered boulder at about 11m depth.
They were quite large for pygmies, around 2cm long, but resembled Pontoh’s and Severn’s in habit. Like these two scientifically named seahorses, the Japanese pygmy is also free-living, but has a unique reticulated pattern over the body that distinguishes it from other members of the group.
I went on to find more than a dozen individuals over the coming week, always in the same kind of habitat. They were in fact one of the easiest free-living pygmies to find, because they protruded slightly from the side of the smooth boulders.
There are many shore dives around Hachijo, but whenever possible we dived the Nazumado site, which is generally possible only in summer.
Tanaka, the owner of Concolor, is passionate about the diversity of the small island’s marine life. There was a well-stocked library but I learned as much from speaking to him.
Besides the pygmy seahorse, Tanaka showed me the beautiful wrought-iron butterflyfish, found only around a few of Japan’s offshore islands and especially abundant around Hachijo.

SEVERAL UNEXPECTED DISCOVERIES included a pair of harlequin shrimp, several boxer crabs, bubble snails and a small school of beastly looking striped boarfish in a large cave at 20m.
I saw none myself, but the deeper areas are frequented by thresher and hammerhead sharks, offering an alternative to the smaller reef creatures.
I went on a morning dive with two guides to hang out where the threshers are commonly seen. The guides both saw the shark, but I must have been distracted daydreaming about pygmies, and managed to miss it!
Regular sightings of hammerheads are reported if you go to the right spot, but currents can be quite strong in these areas.
I only scratched the surface of what Japan has to offer the adventurous diver on this trip. Even Izu and Hachijo offer a different complement of animals during different times of the year.
Many other areas around the country also have great diving with various endemics that remain high on my list.

GETTING THERE: Tokyo and Osaka have the two largest international airports in Japan. Japan Airlines and ANA have a network of domestic routes, including flight to Hachijo. No visa needed.
DIVING: In Okinawa and Izu Richard Smith dived with Kiki Diving Club, kikidivingclub.com. Its main office is in Tokyo. In Hachijo he dived with Concolor Diving, concolor.biz
ACCOMMODATION: Richard stayed in various types of accommodation, from western-style hotels to traditional ryokans or roadhouses.
WHEN TO GO: Typhoon season June-Oct. Most reliable time for diving is Sept-Nov, with good vis and warmer water. Water temperatures drop into the teens in winter, mid-to-high 20s in summer.
PRICES: Inside Japan Tours can offer a nine-night Izu diving package with three nights in Tokyo, five in Shimoda and one in a traditional ryokan in Atami. The price of £1824pp (twin share) includes 12 dives on the Izu Peninsula, off Atami and the Chinsen wreck, Shimoda and Mikimoto (hammerheads in summer) and across the Izu Islands. International flights are extra, www.insidejapantours.com