From Japanese Bullhead Sharks to Dragon Moray Eels! Diving in Isu Oshima

At the start of July, we were in the waters around Izu Oshima. We could see Bullhead sharks, Dragon Moray Eels, and Hammerheads…We were there only for 2 days and one night but its only 1.5 hours away using the high-speed boat from Takeshiba Pier in Tokyo.

After we arrived in the early morning at the island, we had 3 dives, then the next morning grabbing another 3 dives, including being able to see the Hammerhead shark with sunrise, by the time we were back on the boat for going back, we had an 6 amazing dives under our belts! Isu Oshima is simply awesome.

Sea of Izu Oshima・The Undersea Geopark(1)

Sea of Izu Oshima・The Undersea Geopark(2)

Youtube : Dive in Izu Oshima

I was quite worried about the heat during the day, but the water temperature was 19 to 22 degrees ℃ which was fine in a dry suit. While taking a diving short course, we could observe so many fish, and on top of that, get some photos as well. The most memorable thing about the trip was our encounter with the Bullhead sharks.

The Bullheads are quiet-natured sharks, who often live in the seaweed beds. They are commonly seen in Izu while diving. The English name is ‘Bullhead Shark’ but the Japanese name of the sharks are “Neko-zame” which means “Cat (neko) + Shark (same).” It is named this because where the eyes of the shark are pointy like a cat’s ears at the top of the head, the overall shape makes the shark look like a cat’s face.

トラウツボ Doragon Moray 伊豆大島 Izu-oshima

The Dragon Moray Eel.

The English name was ‘Dragon Moray’ but the Japanese named it as ‘Torautsubo’ or a ‘Tiger’ (tora) +’Moray’ (utsubo).

This Green Sea Turtle has been given a name by the locals as ‘The Lord’ (Nushi) because it is so extremely large. Because it is not photographed with a person, it is hard to get the scale of just how big he is, but in all the diving I have done, it is the largest Green that I have ever seen. According to our guide, either he is getting too old or too big, but he just does not move very much from this spot.

Whip Coral Goby

This type of coral is called a Whip Coral and the fish that lives on it is a type of Goby fish.

In Japanese this fish is called a ‘Toshima Gimpo’ (Neoclinus toshimaensis). It is poking its head out of its burrow but only 1cm of it can be seen.

A Hammerhead shark at Keikai Beach. During this trip, we did not see that many of them, but it is always a little startling to see them swimming (we were at 12 meters depth as they passed directly overhead).


Near the access to our diving area, there is a toilet which served as the home for this Pacific Swift nest- it was full. The next day, the babies had fledged and left the nest.

This is the outside of the lodging. There are many cats in this area. It was a very healing stay with nostalgic scenes like this and the friendly cats.

The fish we saw the most during this trip was the Chicken grunt (isaki). We also saw it on the menu at dinnertime!

If you are in Izu Oshima, you should try the bekko rice bowl (Bekkou don). We ate it as our last meal after the final dive, enjoying all the specialty items the island has to offer. There is a pickled sashimi that is placed on top of the sushi rice. And the beer after having a dive tastes so good.

In the evening, we took the ferry back to Takeshiba pier in Tokyo.

Image: Mariko SAWADA
Observation: JUL 2022, IZU OSHIMA
Special Thanks: Beach Line

Related topic       Youtube : Dive in Izu Oshima

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The Sea of Izu Oshima: The Underwater Geopark (2)

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.

Underwater Geopark,Keikai Beach, Izuoshima, 海底ジオパークのようなケイカイを行くオーナー

I was diving in the path formed by the lava flow. This was right at daybreak, the sea is still quite dark.

ハンマーヘッドシャーク ケイカイ浜 伊豆大島 Hammerhead Shark Izu Oshima keikai Beach (4)

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!

ハンマーヘッドシャーク ケイカイ浜 伊豆大島 Hammerhead Shark Izu Oshima keikai Beach (3)

Hammerheads were coming straight towards us. And boy were they close!

ハンマーヘッドシャーク ケイカイ浜 伊豆大島 Hammerhead Shark Izu Oshima keikai Beach (2)

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.

ハンマーヘッドシャーク ケイカイ浜 伊豆大島 Hammerhead Shark Izu Oshima keikai Beach

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?

お祝いの飾り、ハンマーヘッドシャーク 100本記念ケーキ

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

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Sea of Izu Oshima・The Undersea Geopark(1)

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)”.

伊豆大島ダイビング Diving at Izu-oshima 王の浜のケヤリ (3)

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.

ケヤリとテンクロスジギンポ Piano fanglenny 伊豆大島ダイビング Diving at Izu-oshima 王の浜(1)

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.

テングダイ 王の浜 伊豆大島ダイビング Diving at Izu-oshima (2)

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.

テングダイのアゴヒゲ 伊豆大島ダイビング Diving at Izu-oshima 王の浜

Like Long barbeled grunter, it has fine whiskers on its lower jaw, which are said to be skin protrusions.

コケギンポ 伊豆大島ダイビング Diving at Izu-oshima 王の浜

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.

ニシキフウライウオの伊豆大島ダイビング Diving at Izu-oshima 秋の浜 (2)

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!

ニシキフウライウオの伊豆大島ダイビング Diving at Izu-oshima 秋の浜 (1)

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.

ニシキフウライウオのペア伊豆大島ダイビング Diving at Izu-oshima 秋の浜

This is a pair of Harlequin ghost pipefish. The female is pregnant, carrying the eggs in her belly.


The babies of the Palette surgeonfish.

オルトマンワラエビ 秋の浜

Ortmann’s spider-crab.

トラウツボ Dragon Moray 伊豆大島ダイビング 秋の浜 Diving at Izu-oshima (2)

Then, according to our guide Mr. Furuyama, the first thing that foreign divers request to see is this Dragon Moray Eel.

トラウツボ Dragon Moray 伊豆大島ダイビング 秋の浜 Diving at Izu-oshima

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

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The Largest Breeding Ground for the Short-Tailed Albatross: Tori-shima Cruise

⑯アホウドリアホウドリ 鳥島クルーズShort-tailed Albatross Tori-shima Island

This is a report of the Tori-shima Nature Cruise aboard the Nippon Maru.

Our 2021 cruise departed from the Yokohama Port on April 18. It was a 2-night, 3-day cruise that circles around Tori-shima, the breeding grounds for the short-tailed albatross. Of course, passengers are not allowed to land on the island itself, but nonetheless, it is a very rare chance to see such an critically endangered bird, as they are nesting on an island that is so inaccessible. It was totally worth it!

①アホウドリ最大の繁殖地鳥島へ アホウドリ 鳥島クルーズShort-tailed Albatross Tori-shima Island

Heading to the largest breeding grounds for the albatrosses, Tori-shima.

A large colony of albatross lived on the islands until the Meiji Era, when the practice of collecting and killing the birds for their feathers began in 1888. It is thought that by 1902, at least 5 million birds had been overhunted for the feather trade. In 1902, however, the island’s volcano erupted and killed 125 islanders causing the incident to later be called the “Curse of the Albatross.”

Tori-shima was designated as a wildlife refuge in 1933 to help protect the remaining albatross, but the population continued to decline until in 1949, Dr. Oliver Austin published papers in academic journals declaring that the short-tailed albatross was extinct. Everyone believed this to be true until 1951 when the albatross were sighted again on Tori-shima Island. It was a report made by Mr. Yamamoto of the Tori-shima Meteorological Observatory, who sighted about 10 birds who had survived and were breeding.

In the early 1970’s biological research and activities to restore the population of short-tailed albatross began, lead by Dr. Hiroshi Hasegawa, who also joined our same cruise boat as a speaker. The Tsubamezaki nesting site was located on the southern side of the island, on a very steep cliff. This area was often affected by landslides of the sediment from the volcano, making it a very unstable environment for the nests. Therefore, from 1981, vegetation Miscanthus condensatus & Chrysanthemum pacificum was planted on the slopes in order to help stabilize the soil around the nesting area to improve their breeding success. Despite these efforts, even though it was helping, it was difficult for the birds to have a successful brood where the ground was so unstable.

In the 1990s, a different approach to help guide the birds to a new area for breeding on the north side of the island was undertaken. Albatross decoys were placed on the ground and speakers were used to call to and attract the young albatrosses to the more gentle slopes of the Hatsunezaki area. This attempt was successful and produced better results, eventually leading to Tori-shima currently having three colonies: Hatsunezaki, as the main area, the original Tsubamezaki site and a little higher up from there is the Komochiyama site. Short-tailed albatross, which had once been declared extinct, was in 2018, estimated to have over 5000 birds flying over Tori-shima now.

After leaving Yokohama Port at 5 PM, the 19-hour cruise finally arrived at Tori-shima around 12 Noon, the next day. From the deck of the ship, we could occasionally see both black-footed and short-tailed albatrosses flying around.

②鳥島到着前 クロアシホウドリアホウドリ 鳥島クルーズBlack-footed Albatross Tori-shima Island

A Black-footed Albatross seen from the deck of the ship just before arriving at Tori-shima.

③鳥島到着前 アホウドリアホウドリ 鳥島クルーズShort-tailed Albatross Tori-shima Island

An Adult Short-Tailed Albatross

④鳥島到着前 アホウドリの若鳥アホウドリ 鳥島クルーズShort-tailed Albatross Tori-shima Island

A Juvenile Short-tailed Albatross

⑤鳥島到着前 アホウドリの若鳥アホウドリ 鳥島クルーズShort-tailed Albatross Tori-shima Island

A Juvenile Short-tailed Albatross

As the ship nears the island, we were on the north side near the breeding grounds of Hatsunezaki. It was still too far to be able to see any birds with the naked eye, but with binoculars, I could see the birds dotting the slopes and flying above the island. As we got closer to the island, the excitement increased as the crowd observing from the deck, could see the birds also.

⑥北側から見た鳥島 向かって右手に初根崎の新しい繁殖地 アホウドリ 鳥島クルーズShort-tailed Albatross Tori-shima Island Hatsunezaki breading ground

This is Tori-shima’s northern side. The new colony was created called Hatsunezaki is on the right side of the island.

We arrived on the northern coast around 1 PM. We went around the island counterclockwise from there, while listening to Dr. Hasegawa’s explanation over the ship’s loudspeakers. Around that time, we were close enough to be able to see the birds without using binoculars. I could see so many short-tailed and black-footed albatross.

⑦初根崎の繁殖地アホウドリ 鳥島クルーズShort-tailed Albatross Tori-shima Island Hatsunezaki albatross breading ground

The Hatsunezaki Nesting Colony

⑧アホウドリとクロアシホウドリアホウドリ 鳥島クルーズShort-tailed Albatross Tori-shima Island

Short-tailed and Black-footed Albatross gliding over the waves

⑨アホウドリアホウドリ 鳥島クルーズShort-tailed Albatross Tori-shima Island

An Adult Short-tailed Albatross

A flock of short-tailed and black-footed albatross, floating together. This is a sight you would never see anywhere else! The people watching through their cameras and binoculars excitedly say to each other, “This is amazing!” and “I can’t believe it!”

⑩海面に浮かぶアホウドリとクロアシホウドリアホウドリ 鳥島クルーズShort-tailed Albatross Tori-shima Island

Short-tailed and Black-Footed Albatross Flock Resting Together

⑪海面より飛び立つ様子アホウドリ 鳥島クルーズShort-tailed Albatross Tori-shima Island

The flock of mixed albatross takes off together. There seem to be many individuals on the surface that are darker colored, which must be the juvenile birds.

⑫東側から見た鳥島 北側の傾斜が緩やかで、南側が急峻な地形である事が分かるアホウドリ 鳥島クルーズShort-tailed Albatross Tori-shima Island)

Tori-shima as seen from the west side. You can clearly see that the slope on the north side (left) is a gentle rise, while the terrain on the south side is quite steep.

As we neared the south side of the island, we could see the original Tsubamezaki colony. On the steep slopes I could clearly see the area where the volcanic soils were loose and eroding the slopes. The albatross were slowly moving up the slope to the newer breeding area of Hatsunezaki, but there were still about 550 pairs in the perilous area.

⑬島の南側にある燕崎の繁殖地アホウドリ 鳥島クルーズShort-tailed Albatross Tori-shima Island Tsubamezaki Albatross breading ground

The south side of the island, Tsubamezaki Colony

⑭燕崎の繁殖地拡大アホウドリ 鳥島クルーズShort-tailed Albatross Tori-shima Island Tsubamezaki breading ground

Close up of the Tsubamezaki breeding area

Since there are no colonies on the east side of the island, the number of birds seen from the boat have become less frequent. As we neared the end of the tour around Tori-shima, the crowd on the deck could be overheard saying, “I wish we could go around one more time.” According to Dr. Hasegawa, if things go smoothly, they expect the population to recover to around 10,000 birds by 2026. Being able to see this process with my very own eyes was a really impressive and exciting process! I hope that by next year, the cruise can make 2 laps around the island!


Photo & text: Kengo YONETANI
Observation/Cruise: 18-20 April 2021 by Nippon-maru, Tori-shima, Izu Islands, Tokyo, Japan

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