Diving in Izu Oshima. The special here is that you can see Hammerhead sharks by the beach dives.
Dive in Izu Oshima｜ Hammerhead shark Izu Oshima Diving
This is the entry point of the lava coast, a trail made from the lava flow that is a maze-like diving path. This is where you can see where the namesake “Underwater Geopark” comes from.
I was diving in the path formed by the lava flow. This was right at daybreak, the sea is still quite dark.
As soon as we were in the water, we could see the hammerhead sharks. They appeared, one after the other, in a group of 5 and then up to 30 individuals. At about 15m (50ft) depth, we could feel the current of the tide coming on but I was clinging to a rock to keep observing the sharks. Even beginners, could have a good chance to see the sharks here so it is a really great spot!
Hammerheads were coming straight towards us. And boy were they close!
Every morning, immediately after the sunrise is the best chance to encounter these hammerhead sharks. They are seen in the area from mid-June to mid-October, and we went diving 3 times, and saw them each time.
Perhaps they are aiming for the first meal of the day at some first class feeding spot, rising from the depths along with the rising sun?
This was a little cake decoration to commemorate the 100th dive of one of our tour members. It was an image of the “Keikai’s Hammerheads” handmade for them by the Saiyu staff.
Image & text : Mariko SAWADA
Observation : Sep 2021, Keikai Beach, Izu-oshima, Tokyo, JAPAN
This is my report of diving in Izu Oshima. You can get there by jet foil boat in only 2 hours and is so surprising that it is this close to Metropolitan Tokyo.
It is a paradise for various sea creatures, which is great for photographers. The first thing we wanted to see was the Hammerhead Shark in the early morning hours, but I could also observe other things at the diving spots “Ou no hama 王の浜 (Kings Beach)” and “Aki no hama 秋の浜(Autumn Beach)”.
This is a type of seaweed called ”KEYARI” in local language, Sporochnus radiciformis that we saw from “King’s Beach 王の浜”. It is a popular subject for photo enthusiasts because of its beautiful peacock-like feathers, if you can manage to creatively get the right angle with some technique. It is widely distributed in the Japan sea, but it is said that the areas where the Kuroshio current passes through are more colorful.
Then this Piano Fangblenny who shares the area with the S. radiciformis. These little fish are found on the Pacific side of Japan and are only about 10 cm (4 inches) long. I saw in the same place, two times, but it never showed its entire body. This pose, poking it’s face out and with the S. radiciformis in the background was irresistibly cute.
At “Ou no hama 王の浜” (King’s Beach), we also saw the Banded Boar head, a fish that stands out and grows to about 50 cm (20 inches). These were quite accustomed to divers.
Like Long barbeled grunter, it has fine whiskers on its lower jaw, which are said to be skin protrusions.
Just as I was leaving the King’s Beach 王の浜, I stopped at this structure “Rock of Moss Fringehead.” This super cute and tiny collection of Moss Fringehead captured many divers attention and we were all trying to get a good photo while being swayed by the waves and current.
It was “Aki no hama 秋の浜 (Autumn Beach)” where I could observe the most variety creatures (it is also popular with other divers because of the easy access point).
This is a Whip coral goby attached to the whip coral.
And diving to a deeper level, this Harlequin ghost pipefish could be seen. It’s hard to see because it’s camouflaged to look like the coral!
The male Harlequin ghost pipefish mimics the coral almost exactly. They are a member of the Solenostomidae family, and was previously thought to be an intraspecific mutation, but in 1994, they were named as a separate species.
This is a pair of Harlequin ghost pipefish. The female is pregnant, carrying the eggs in her belly.
The babies of the Palette surgeonfish.
Ortmann’s spider-crab.
Then, according to our guide Mr. Furuyama, the first thing that foreign divers request to see is this Dragon Moray Eel.
The Japanese name of this fish is “TORA-UTSUBO”, translated as Tiger moray eel. To me, it doesn’t look like a “tiger”, (the pattern seems more like a leopard), and the name “Dragon” seems accurate. But perhaps the most accurate description could be the “Qilin” which appears in Chinese mythology?
Photo & text: Mariko SAWADA
Observation: Sep 2021, Izu-oshima, Tokyo, JAPAN
This is a report of a diving trip in Amami Oshima in May. The main focus of this trip was for observing the white-spotted pufferfish, Torquigener albomaculosus. Ten of the 15 dives were to witness the process of circle-making pufferfish, and the remaining 5 dives were planned for seeing the other spectacular creatures of Amami.
This is the season for broadclub cuttlefish spawning. Originally, I was planning to observe the broadclub cuttlefish but this year their numbers was so small that we could not see group spawning that typically happens. Behind the Porites cylindrica are some broadclub cuttlefish eggs. You can see the baby inside, it’s still so very small.
コブシメの体色変化 color change of Broadclub cuttlefish
The amazing ability of the broadclub cuttlefish to change colors is interesting. When I get too close to it, it expresses its bad mood and turned black, but after I moved off a little, it started to mimic the surrounding, lol!
Swimming male Red Fairy Anthias Pseudanthias cooperi, which were at the bottom of a sandy area. The school of Luminous cardinalfish, Rhabdamia gracilis so beautifully swimming and framing the background.
Right at the edge of the reef, a big school of Golden sweepers, Parapriacanthus ransonneti.
Photography by Chizuko MURATA
I photographed the nudibranch Hypselodoris bullockii on a red sponge. It looks like a pattern on a Japanese traditional cloth.
Photography by Chizuko MURATA
One of the highlights of this diving spot is that we can see pygmy seahorse, Hippocampus bargibanti at a shallow depth of 15m. This pygmy seahorse, which attaches to the red or yellow soft coral. It will mimic with amazing accuracy and becomes the same color as the coral, even mimicking the polyps. When it was first pointed out to me in Ogasawara, I could not even see it, but now, after several opportunities to see it, over and over again, I have gotten just a little better at spotting it.
And this is the “Great Buddha” Coral. It is a large common coral group called Pavona clavus.
The Amethyst anthias, Pseudanthias pascalus schooling above the coral.
The breeding colors of an Amethyst anthias male with a yellow tail
ハナゴイ乱舞 Purple queen wild dance（Videography by Chizuko MURATA)
It was so spectacular to see the little Amethyst anthias, which looked like falling rain at times.
The Bubble coral shrimp Vir philippinensis. It was holding an egg.
And the highlight of this tour, is the observation of the white-spotted pufferfish circles. The ocean bottom is a fine sand, and you have to be very careful about not messing it up. After staying a while, it will become cloudy.
A rainy day with poor water clarity, looks like this. Because of the depth and the risk of having bad visibility, those who want to observe the pufferfish closely, should make sure they have multiple diving chances.
Putting the finishing touches on the pufferfish’s circle.
This is the completed circle. For these small fish to do all the work using their bodies, who work on the circle and don’t seem to look at it from above, it is quite an impressive feat.
Now, it is just about attracting the female. This is the diligent male white-spotted pufferfish.
The next day, in the center of the circle where the eggs were laid (the gray mass in the middle). After this, the male will take care of the eggs and the circle will no longer be maintained.
I stayed at Amami Oshima for 6 consecutive nights, and I was really looking forward to the daily meals. Every day is a glorious feast! Octopus, cuttlefish, yellowfin tuna, other seabream species, green turban, … the list goes on!
It was rainy season in Amami Oshima, but during this diving tour we made sure to plan a way to enjoy the ocean and the bounty of food it provides. Thank you to everyone who joined the tour, to our underwater guide-Dive Species Amami, Mr and Mrs. Suwa!
Images & Text: Mariko SAWADA
Some photographs and video: Chizuko MURATA
Observation: May 2022, Amami-Oshima
Special Thanks: Dive Species Amami, Mr. Homare SUWA
These “Mysterious Underwater Circles” of Amami Oshima became a hot topic when a TV program introducing them was broadcasted. Originally found by an underwater photographer in 1995, he didn’t know who made them and for what purpose they were there. It was in 2011, that we finally discovered that it was made by small pufferfish.
The Amami Oshima’s “Mysterious Underwater Circle” is often made nearly 30m deep, so it is hard to observe for long at that depth; and the seasons and tides limit the divers’ abilities to observe these circles, so it took 16 years before we were able to meet its creator, the pufferfish.
This is the male pufferfish, Torquigener albomaculosus, the creator of the circle. In 2014, this pufferfish was registered as a new species. The Japanese name “Amami Hoshizorafugu” is named so because of the dotted pattern on its back, like the many stars in the beautiful night sky of Amami Oshima. (In Japanese “Hoshizora”= starlit night sky, “fugu” = pufferfish)
We observed this white-spotted pufferfish over five days, as it was constructing the circle. In this photo, the pufferfish is decorating the outer edge of the circle with shells. It seems that the fish shapes the shell by chewing on a larger shell in its mouth.
The first step in creating the circle, is for the pufferfish to choose a spot that it likes and begin by removing and seaweed from the area. Then it will make a groove which will be the basis of the circle. For the making of the outer circle, the groove is formed by the small fish using its pectoral fins to roll up the sand moving from side to side. Slowly, the sand is piled up on both sides to form a deeper groove.
The center of the circle, where the eggs will be laid, is made into a gentle shallow area using its stomach.
White-spotted pufferfish which has finally finished making its circle. But even then, it’s very busy with maintenance to keep the shape.
Now it is just a waiting game, until a female pufferfish comes by and likes his circle!
At this time in May 2022, during high tide there were seven circles in the diving area. This morning, one male had success as there were some eggs in the middle of the circle! The gray color mass in the middle of the photo are the eggs.
As soon as the female lays the eggs, she disappears and the male will take care of the eggs in his circle. He will consistently move the eggs and sand with its fins and continue to send them fresh seawater.
A male white-spotted pufferfish who is busy taking care of his eggs. The maintenance of the circle stops and therefore the shape is starting to collapse a little.
So, in this 30m deep area where we were diving, we could see 6 of the 7 circles had eggs. But the one that had no eggs yet, which we nicknamed “Fuguta,” this was the circle that I thought was “the most beautiful and splendid circle” but sadly, it wasn’t chosen by a female pufferfish. I am sure there is a difference between the pufferfish and our senses, but even so, I was disappointed that it was not selected…it was like a Japanese saying that “it was the crowd favorite, but it failed to qualify for the finals.”
Our little “Fuguta,” who was dedicated to the maintenance of his circle. He was laboring over it, however, he wasn’t as energetic as yesterday.
“Fuguta” would not give up! The breeding season will continue for another two months. I left the seabed praying for him, that he’ll be able to attract another female during the next high tide.
Of the 15 dives over a 5 day period, 10 dives were spent observing the white-spotted pufferfish. We observed all the various stages from circle construction, the maintenance, and then of taking care of the eggs. It looks a very smart fish.
Photos & text: Mariko SAWADA
Observation: May 2022, Amami Oshima
Special Thanks: Dive Species Amami, Mr. Homare SUWA
In May, I visited the Aguni Islands for the bigeye trevally season. We not only got to see schools of bigeye<GINGAME-AJI> making a tornado of fish, we also got to see the giant trevally <ROUNIN-AJI>as well as school of dogtooth tuna<ISO-MAGURO>. There were breeding colored bigeye trevally and the sea was bursting full of life!
DIVE IN AGUNI ISLAND 粟国島の海
Image & text : Mariko SAWADA
Observation: May 2021, Aguni Island, Okinawa
When talking about “Scuba diving in Ogasawara Island,” it is almost synonymous as saying “Sand Tiger Sharks.” (shirowani in Japanese). They are bottom dwellers, normally found in small caves but encountering them in a shipwreck dive is quite dramatic.
In Chichijima -Futami Bay, there are many ships that were attacked during World War II. Just diving around these wrecksites can be impressive enough by itself, but add in a sand tiger shark or two and it becomes exceptional.
Sand Tiger Shark at Shipwreck, Bonin island Japan｜西遊旅行
There are many different ways that the ships may have ended up on the bottom; some have fallen apart as they sank after having been hit directly, some that sank in their original upright position, and yet others that are completely on their side when they sank to the seafloor.
Sand Tiger Sharks have their favorite places where they like to hang out, and sometimes we got to see more than one at a time!
The sharks swam over me slowly and it really gave me the chills! I want to keep watching this scene, but I must get ready to surface. We are in the deep water, so we cannot linger here too long and must start making our slow ascent back up to the surface.
Our last moments with the Sand tiger shark!
This was the last one we saw, who was swimming among the Striped jack. Right after we saw this Shark, we returned to the surface.
Image & text: Mariko SAWADA
Observation: Oct 2020, Chichijima, Futami Bay, Ogasawara Islands
We observed this pair of Banded pipefish in Yakushima’s Isso bay. The pipefish have a white body with many reddish-brown horizontal stripes that cover it from the mouth to the tail fin. The gorgeous tail fin reminds me of the beautiful “Oiran” that Japanese high-ranking courtesans use.
オイランヨウジのペア（屋久島）A Pair of Ringed pipefish
The male banded pipefish has a pouch that incubates the eggs. There can be up to 100 eggs which hatch after about 10 days. The fries are about 6mm when they emerge.
Banded pipefish eat zooplankton. The entrance to this pair’s rock crevice was surrounded by little tiny fries and they were busy feeding on them.
Image & text: Mariko SAWADA
Observation: Jun 2021, Yakushima, Kagoshima
We could see a pair of Harlequin ghost pipefish (Solenostomus paradoxus) in the seas around Yakushima. The pair were in perfect unison with their mimicry, which made it both astounding and beautiful to watch.
ニシキフウライウオのペア（屋久島）A pair of Harlequin ghost pipefish
Harlequin ghost pipefish is a member of the family Solenostomidae. The Solenostomus were previously thought to be an intraspecific mutation within Solenostomidae but, they became an independent species in 1994.
On every part of the body and along its fins, there are spikes that stick out, with spotted patterns as well. The body is a white color with some transparent areas, but the designs and patterns that appear are so diverse!
The larger one is the female, and the smaller one on the right is the male. Unlike the pipefish, where the males incubate the eggs, in family Solenostomidae, they leave the job of protecting the fertilized eggs to the females with the larger pectoral fins.
In English, the name of the fish is “Harlequin ghost pipefish” or “Ornate ghost pipefish,” but in Japanese they are called “Nishiki fuurai-uo.” “Nishiki” refers to a traditional Japanese weaving textile, highlighting the intricate designs seen on this unique fish.
Image & text : Mariko SAWADA
Observation : Jun 2021, Isso-bay, Yakushima, Kagoshima
The Hasama Underwater Park is located just on the border between Tokyo Bay and the Pacific Ocean, and it is within 2 hours travel time from the city center. The Underwater Park is rich with fish because of the input of nutrition from the freshwater rivers and the Kuroshio Current running along the coast of Japan. This place is quite famous for the underwater shrine Torii and ‘Yoriko’ the Asian sheepshead wrasse.
YORIKO Asian sheepshead wrasse コブダイの頼子・波左間海中公園
The Asian sheepshead wrasse is called “Kobudai” in Japanese (as if it was a member of the Sea Bream family), it is a member of the wrasse family, and is a “hermaphroditic” species which can change sex between male and female. It first matures as a female and breeds, then changes sex to a male and participates in breeding again.
This “Yoriko” used to be a female paired with a male named “Yoritomo,” but one day “Yoritomo” disappeared perhaps because he lost the battle for territory. Following that development, “Yoriko” then became a male and has stayed that way to the present day. The lifespan of the Kobudai is thought to be about 20 years long, but “Yoriko” has already exceeded 30 years of age. He has come to be a very cherished and well-loved fish at the Hasama Underwater Park and taken on a mystic-natured creature who time has forgotten.
This is the famous underwater shrine, the only kind in the world, in the Hasama Underwater Park. It is an authentic shrine that was built in 1997 as a branch of the Susaki Shrine in Tateyama.
Another famous place in the Hasama Underwater Park is the “Sea Pen Colony” (in Japanese it is called ‘Yanagi-umiera’). It was the first time I could see these! Depending on the tide, it may or may not appear on the surface of the sand, so I felt so lucky to see the colony. The English name “Sea pen” is because of the resemblance to a Quill pen!
A colony of the Sea Pens Virgularia halisceptrum .
There are many other areas for great fish sightings as well. There is a fish-reef called “Dream” where the scenery created by the soft corals and Sea goldie, as well as Redbar anthias and Cooper’s Fairy Basslets. 。
This is the Spottedtail morwong cleaning station. The name for the fish in Japanese is “Takanoha dai” derived from the Japanese word for “Hawk feather” which is “Taka no ha.” This is based on the similarity of the stripes that are seen on hawk feathers, The polka dots on the tail also really catch my attention.
Here is a friendly pair of redlip morwongs.
Image: Mariko SAWADA
Observation: Jun 2021, Hasama Marine Park, Tateyama, CHIBA
Japan’s westernmost island is the Yonaguni Island. It is said that on a good visibility day in the summertime, you can see all the way to Taiwan. One of the things that make Yonaguni famous, are the schools of Hammerhead Sharks that can be observed here while diving.
We visited early April, which is the end of the hammerhead season, so we thought it would be difficult to encounter them, but we were able to see many schools multiple times.
An unexpected encounter with a large school of hammerheads.
The hammerhead sharks at Yonaguni Island are all females and are generally calm and do not bite. Usually, they are found swimming at a depth of 35m to 40m, but this time we could encounter them at a relatively shallow depth of 25m to 30m.
Of course, while diving, we also visited the ‘Yonaguni Underwater Monument.’What looks like a terrace cut at right angles, looks man-made, but the natural formation is not actually a ruin. It is found in a spot that has a fast moving tide.
We stayed at Guesthouse FIESTA, where the owner prepared a wonderful BBQ for us.
The Yonaguni marlin are also famous. There are also many fishing boats that mainly target the marlin. We could get some fresh sashimi from the local Kinjo Tackel Shop. During our stay, we could also enjoy the fresh greater amberjack and green jobfish
We also had some locally produced ‘Island tofu (Shima tofu)’ cold and the last of the seasonal ‘Island Coriander/cilantro (shima pakuchii).’
This baby goat isn’t on the menu! This is the 2-month old goat of the Dive Shop Marlin, and it has been guaranteed the lucky designation as a lifelong pet.
Image & Text: Mariko SAWADA
Observation: Apr 2021, Yonaguni Island, Okinawa
Special Thanks: Yonaguni Diving Service MARLIN, Guesthouse FIESTA
