Diving in Japan is diverse, with temperate waters in places such as Izu Oshima in the Tokyo Islands, and warmer, tropical waters in Okinawa. Pierre Constant tells of his visit to these two disparate locations and the variety of marine life he encountered at each.
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It was a long, overnight flight from Amsterdam to reach Japan. The plane landed at Tokyo Narita Airport mid-morning. An intimidating monster-city of concrete, steel and glass, Tokyo had surprisingly clean and tidy streets dotted with several parks and green areas. Expecting my arrival, my Japanese son, Kirin Sekito, met me there, accompanied by his lovely 7-year-old daughter, all smiles. A professional underwater photographer and videographer, Kirin is a rising star in Japan, with many followers on social media. He would be my official guide for the next nine days on this dive trip. Our primary destination would be Izu Oshima, one of the Tokyo Islands south of Tokyo, ending the trip with a visit to Okinawa in the Ryukyu Islands.
About Kirin
My last journey to Japan was 23 years ago. I recall Kirin always loved the water. At the age of four, he joined one of my cruises in the Galapagos Islands. He was not afraid to jump into the waves off the beach and splash around like a little puppy dog. A few years later, he could swim ten metres underwater on a single breath. When he was 17, I introduced him to scuba diving in the Galapagos in 2005, and it opened a window to a new dimension for him.
One day, Kirin decided to become a scuba diving instructor. He worked for some time as a Japanese dive guide on the Great Barrier Reef in Australia, learning English in the process. Since then, he has lived with his Japanese family in Japan. We lost track of each other for many years after that, and life moved on.
On to Izu Oshima
We departed one morning from the Takeshiba Ferry Terminal. Facing the southwest trade winds in August, the fast crossing on the Jetfoil would take one hour and 45 minutes. It was a smooth ride in comfort. A Honda minivan was conveniently at our disposal at the Motomachi port car park.
Kirin turned the ignition key, and we were off with all our bags and equipment. Yellow Dive, the dive centre run by Toru Furuyama, was barely 10 minutes away, out of town and nestled in a natural countryside setting, surrounded by forest with small muntjac deer wandering about. It was a haven of peace, which, besides the dive centre, provided accommodation, a lounge, a kitchen area and a relaxing open-air salon outside.
Toru and Kirin have been friends for many years. Formerly a fisher of spiny lobsters, abalone and turban shells, Toru has officially been a PADI scuba diving instructor since 2001, his main job for the past 24 years. Always ready to help, this charming man, along with his wife and little dog, Mugiko, made me feel at home right away. I settled in at the Komugi Villa in the garden, which was an exquisite wooden chalet with twin beds and a salon-mezzanine above, furnished with a table, chair and stool. It would be my private quarters for the next eight days.
Volcanic nature of Japan and Izu Oshima
Japan is situated at the crossroads of four major tectonic plates: the Okhotsk (North American) Plate to the north, the Amur (Eurasian) Plate to the west, the Philippine Plate to the south, and the Pacific Plate to the east. The Pacific Plate subducts beneath the Okhotsk Plate at the Japan Trench, creating a conspicuous earthquake epicentre on the east coast.
The Philippine Plate subducts beneath Central and Southwest Japan at the Sagami Trough, Nankai Trough and the Ryukyu Trench. The oceanic Ryukyu Trench is found along the southeastern edge of Japan’s Ryukyu Islands in the Philippine Sea, extending from northeastern Taiwan to southern Japan. This, in short, explains the volcanic nature of Japan.
Izu Oshima is an island located south of Tokyo on the eastern edge of the Philippine Sea Plate, 22km east of the Izu peninsula and 36km southwest of the Bōsō peninsula. A “hotspot” in geological terms, Izu Oshima is an active volcanic island, the remnant of three stratovolcanoes.
The last eruption of Mount Mihara took place in 1990, following a major eruption in 1986, which caused widespread lava flows. I intended to climb the volcano, but continuous cloud cover shrouded the top of the island for the first five days. I would have to be patient.
Currents
In the northwest Pacific, the North Pacific Gyre influences the movement of the marine currents. Depending on the time of year, two major currents affect Japan. Coming down from the northeast along the Kamchatka Peninsula, the cold Oyashio Current affects the eastern coast, diverting east at the Chiba Peninsula to join the North Pacific Current.
Coming from the southwest along the Philippines and the Ryukyu Islands, the warm Kuroshio Current is in fact a branch of the North Equatorial Current, which flows from east to west across the Pacific and along the equator. In the northern hemisphere, it is the Coriolis Effect that gives a clockwise direction to this major current. Mostly active during the summer months, the Kuroshio brings warm water from the equator and drifts east upon meeting the Oyashio Current at the Chiba (a.k.a. Bōsō) Peninsula.
One of the largest and strongest currents in the world, the 100km-wide Kuroshio (or Black Current) flows at 2 to 4 knots on average. It brings tropical and nutrient-rich waters northward up towards the polar region. Mostly productive in terms of marine life, it has an average temperature of 24°C. Alternatively, the subarctic Oyashio Current has a temperature ranging from 0°C in early spring to about 20°C in summer.
Dive sites
Akinohama. Prone to jet lag, I woke up every day at 5 a.m., but I did not mind. On the first day, Kirin drove me to Akinohama (Spring Beach), his favourite dive site on the northeast coast of Oshima Island. From the car park, among cypress and pine trees above, a short walk took us to the black basaltic seashore. On the left side of a lava extension, a rusty iron ladder plunged obliquely into the waters three metres below.
“This is where we come up after the dive,” informed Kirin, as I gazed with stupefaction. “But we can enter easily from the rocks on the right side.”
I donned my 5mm wetsuit, yet Kirin was fully prepared in his drysuit! Needless to say, I got quite a shock upon jumping in. The water turned out to be 17°C, and soon enough, I felt uncomfortable.
The rocky bottom was uninspiring and covered in broad, orange-brown algae that swayed in the swell. Fortunately, I noticed several interesting fish species, which I related to my experience of South Australia, such as the spottedtail morwong (Goniistius zonatus) with orange diagonal bands and the redlip morwong (Goniistius zebra), which was yellow with black diagonal bands. Many were rather tame.
There were blacktip groupers (Epinephelus fasciatus). The yellow boxfish (Ostracion cubicum) and longhorn cowfish (Lactoria cornuta) were common, as well as the blacksaddle goatfish (Parupeneus ciliatus), which was often seen in small schools, and the black-blotched porcupinefish (Diodon liturosus).
Absolutely new to me were the Japanese butterflyfish (Chaetodon nippon), the barred knifejaw (Oplegnathus fasciatus) and the spotted knifejaw (Oplegnathus punctatus), which I related to a similar-looking species in the Galapagos Islands. Stunning was the Japanese parrotfish (Calotomus japonicus) in red, grey-green and white, whose range extends from the northwest Pacific to Korea and Japan.
After 30 minutes, I felt quite frozen and chose to return to the shallows. Just before the safety stop, a red stingray (Hemitrygon akajei) came up under me. How to climb up the ladder with only one hand, while the other held my fins and camera, was not that obvious. I managed, though, puffing like a sea lion. Not too sure about a second dive, I was skeptical when Kirin reassured me, “We’ll dive the northwest coast. It should be warmer.”
Nodahama was quite an improvement indeed, as the sea surface temperature rose to a balmy 23°C. A black sandy beach with basalt cobblestones and tongues of black reef jutting out to the west, it was a shallower dive in the 12m depth zone, with an underwater rope helping you out past the surf break.
The highlight of the dive was a submerged arch with a concentration of yellow-finned, threeline grunts (Parapristipoma trilineatum), also known as Isaki in Japanese (a sushi delicacy) or chicken grunts in English. Native to the western Pacific, the juvenile has three conspicuous black lines on the upper back.
Further away, we swam over a sandy patch in search of hammerhead sharks. No luck with that. Instead, a small school of amberjacks, or longfin yellowtail (Seriola rivoliana), called in, which I had often encountered in the Galapagos.
Upon return to Motomachi, we purchased a “bento” (lunch box) of rice with fried jack and shrimp at a little local takeaway shop, which we would come back to every day! The afternoon was spent at leisure, downloading and editing the photos on the laptop, and searching for scientific names out of an excellent Japanese fish guidebook, albeit with no English whatsoever!
Onohama (King’s Beach) was on the western coast south of Motomachi. Gearing up at the car park, we walked down a flight of wide steps to the water’s edge. Kirin led me offshore for a 100m swim to a patch of flower-like seaweed with yellow and blue hearts crowned by fine hairs (Sporochnus dotyi), which I mistook initially for anemones! These moved with the swell on top of a rocky outcrop at a depth of 17 metres. Rising from the seaweed patch with an inquisitive stance, a Kidako moray (Gymnothorax kidako) checked me out with a cool stare. A couple of exotic Japanese (striped) boarfish (Evistias acutirostris), yellow with black stripes, were hiding under a ledge. I marvelled at the colourful Japanese angelfish (Centropyge interrupta).
Kei Kai, our successive dive, was south of Nodahama. A famous site for hammerhead sharks, if you are courageous enough to get up early in the morning at 4 a.m. for a dawn encounter! The rocky beach had a stony entrance in shallow water between boulders into the surf zone. Not easy. We aimed to look for the Japanese wobbegong (Orectolobus japonicus) but tried in vain. Acropora sp. table corals and Dendronephthya sp. soft corals in blue, red and white colours ornamented the sea bottom. The water temperature was 21°C.
Akinohama, revisited. A return to Akinohama, Kirin’s favourite site, was mandatory since the visibility was noticeably better. Mentally prepared for cold water, I was surprised by the 20°C temperature as we dived down to a sandy slope at 20 metres.
Camouflaged and powdered with sand, the mimetic Japanese angel shark (Squatina japonica), which was grey-brown and fully spotted, rested in oblivion. Its range extends from the northwest Pacific to Korea and Japan. Blending into the background, the creature was motionless as we zoomed in for photos. Do not dare to disturb it, for it is known to bite! Kirin gently brushed the water over the top of its head to remove some sand, and its colour pattern appeared clearly.
On dive two, we headed deeper into the 30m zone, where thresher sharks were known to cruise by. Water temperatures dropped to 16°C. Several white Dendronephthya sp. soft corals stood erect on the ridge like joyful Christmas trees with their swarms of orange basslets or sea goldies (Pseudanthias squamipinnis).
For some reason, my camera froze beyond 30m, and I could no longer take pictures. Back at the minivan, Kirin introduced me to Yotaro Mochidzuki, a local thresher shark specialist, who showed me a video he had just taken. Some guys have all the luck.
Toshiki. The southern tip of the island is on the circular road that meanders around the periphery of Oshima. The approach to the water’s edge is on precarious rocks and boulders, slippery when wet. As we threaded through a shallow fjord, Kirin spotted a dragon moray. I pulled myself on a rope across the surf zone, and soon we were on the drop-off, nine metres deep.
Taking a right, I came across some basaltic organ pipe formations. The place was full of green sea turtles (Chelonia mydas) dozing among the endemic dark green Hirome algae (Undaria undarioides) carpeting the bottom. Schools of threeline grunts cruised silently overhead. The visibility was far from fantastic, and we did not linger out there too long. Back into the shallows, a Spanish dancer (Hexabranchus sanguineus) was a welcome sight.
Topside excursion
Finally, the top of the island cleared up, and I decided to make a visit to Mount Mihara. A good tar road climbed in hairpin turns through the native forest, reaching the rim in 15 minutes. However, Kirin suddenly felt dizzy. “I cannot accompany you and must go down at once,” he said. In truth, he had been doing three to four dives a day over the last five days, and he did not fancy risking decompression illness. “I’ll be picking you up later on around 10 a.m.”
The central volcano stood erect in the middle of a 4km-wide caldera. I set off on a descent into the caldera. I met a snake basking in the sun and hiked up to the rim of Mount Mihara in 30 minutes. Passing a single fumarole, the circular loop around the crater took me one hour, under the watchful eyes of the Japanese black kites (Milvus migrans lineatus) hovering above timelessly. The maximum elevation, at 758m, was marked by a wooden post in Japanese “kanji”, carved in white characters.
To the southeast, the perfect cone of Toshima Island rose in the distance among the clouds. Serenity permeated the place, and good, fresh air was a bonus. Not a soul around. To get back to the car park early, I started walking downhill. A few Japanese macaques posed on a railing along the way. But there was no trace of Kirin until I got back to Yellow Dive in Motomachi two hours later. He had not been in any condition to ride up the mountain again and had to breathe oxygen to recover. Better safe than sorry.
Underwater finds and dining delights
Akinohama was on the menu for the next couple of days, but we saw no thresher sharks. Instead, I came across a crocodilefish, the Japanese triplefin blenny (Helcogramma nesion), the cupid wrasse (Thalassoma cupido), the pale-barred coris (Coris dorsomacula) and the red-naped wrasse (Pseudolabrus eoethinus). Last but not least, the highlight would be the Japanese pygmy seahorse (Hippocampus japapigu), red-orange, white and pink in colour. A jewel for the trained eye!
A memorable final dinner with Toru at a local pizza place allowed me to meet two other dive operators in Izu Oshima, including Masashi and his wife, Keiko, and Yotaro (the thresher shark specialist) and his wife, Saci. We had a great time together with laughter and humour, beer, Italian red wine and six different types of Japanese-sized pizzas, which we all shared with the joyful camaraderie of fellow divers. Not to mention pistachio ice cream for dessert! It was a sophisticated and generous sense of hospitality—impossible to forget.
Okinawa
A distance of 2,120km separates Tokyo Haneda Airport from Okinawa in the southwestern part of Japan, a 2.5-hour flight with All Nippon Airways on a Boeing 737 airplane. Distant from continental Japan, this tropical world is part of the Ryukyu Islands chain, which shares the same latitude as the northern portion of the Philippines. Here, the climate is hot all year round, the ocean is blue, and the sea surface temperature averages 27°C to 29°C. No need for a wetsuit for me, although Japanese divers usually wear one.
Run by friendly Akinobu Tsuji, Sawasdee Dive Centre was located in the heart of Naha, the capital city of Okinawa. The island was well known for its various American military and air force bases, but people did not really speak English here. However, its development as a major international port was evident.
I was to spend four days in Okinawa, including three full days of diving. Having worked in Okinawa years ago, Kirin would be my guide and interpreter, and he knew Aki very well. On day one, we were off to the Chibishi Islands. Sawasdee’s dive boat had a capacity of 10 divers.
Dive sites
Watermelon. The Watermelon dive site was a succession of parallel coral ridges in between white sandy channels at a maximum depth of 20 metres. At once, I realised the fish life was poor, most probably due to overfishing for the last 50 years, since the big city was just half an hour away. So, it was mainly small reef fish on this dive. However, the coral luxuriance was awesome, very healthy and colourful. There were lots of table and staghorn corals, among others, with the occasional gorgonian and soft corals.
Whitetip reef sharks (Triaenodon obesus) cruised by leisurely. Particularly exciting was the presence of numerous Chinese sea kraits (Laticauda semifasciata), or Irabu in Japanese, hunting on the reef and oblivious of divers. With a venom stronger than that of the cobra, these light blue and grey-banded sea snakes were harmless. They may be attracted to you out of curiosity. Just give them space and do not disturb them. Because of their small mouths, the only place where they could possibly bite you is between the fingers!
Two dives took place in the morning, followed by a break on the boat, where everybody brought their own bento box lunch. A third dive was conducted in the afternoon with charming guide instructor Anna, or with Aki himself. Most of the divers were women, except for Chohé, an energetic 83-year-old man!
Nagannu Island. Day two saw us head further away to the Kerama Islands, with a first dive at Nagannu Island, a white sand bar emerging above the surface. At the Nippulu Max dive site, I was graced by an encounter with the harlequin tuskfish (Choerodon fasciatus), a wrasse with grey and red bands. An inquisitive Chinese sea krait foraging over sand allowed good photo opportunities with Kirin.
Kuroshima Island, on the successive dive, was a volcanic island, rising picturesquely above the ocean. Notable black cliffs were topped by green vegetation and grasses. Underwater, the scenery was quite different, with walls covered in small orange soft corals, circular red sponges and gorgonians adorned with feather stars. Schools of yellowfin goatfish (Mulloidichthys vanicolensis), orange-rimmed juvenile pinate batfish (Platax pinnatus), pinktail triggerfish (Melichthys vidua), clouds of damselfish, orange scalefin anthias (Pseudanthias squamipinnis) and parrotfishes. The site seemed popular with other dive boats.
Utchisan was a low-lying emerging rock near Kuroshima Island. There was great visibility underwater with two very curious giant jacks (Caranx ignobilis), which used to be fed in the past. “I almost lost a finger to one of these,” confirmed Aki, who warned us.
The highlight of the dive was a bommie that was apparently a cleaning station for various species of fish. Approaching very closely without scaring the fish, I noticed the occurrence of Pacific drummers (Kyphosus pacificus), oriental sweetlips (Plectorhinchus vittatus), the eyestripe surgeonfish (Acanthurus dussumieri) and spotted knifejaw. There was a school of yellowfin goatfish with a large school of paddletail snappers (Lutjanus gibbus) hovering in the background. However, my camera battery suddenly went flat, and I missed out on several good shots.
A light rain welcomed us the next morning. The ocean south of Naha was a bit choppy, so Aki decided our three dives for the day would be at the Chibishi Islands again, where there were coral gardens on ridges with sandy channels in between. On the dives, I took decent shots of the ringtail wrasse (Oxycheilinus unifasciatus) and the barred thicklip (Hemigymnus fasciatus).
Good times
In good Japanese custom, the last dinner was spent with Aki, Kirin and the dive group at the convivial Hamasaki restaurant, sharing drinks or “awamori” (the Okinawa rice wine) and snacks, before an array of exquisite, selected dishes and Okinawa specialities. It was a memorable evening where sharing good times was definitely a must and part of the Japanese culture. ■
Special thanks go to Toru Furuyama at Yellow Dive in Motomachi, Izu Oshima; Akinobu Tsuji at Sawasdee Dive in Naha, Okinawa; and underwater photographer and videographer Kirin Sekito (wildkirinphotography.com).
