Northern Honshū’s Tōhoku (North-East) region offers remarkable underwater environments, with mostly dry-suit, cool water diving in the northern parts, and seasonally warmer waters to the south.
This is especially true on the Sea of Japan side, where waters can rise up to 28°C in summer months thanks to the Tsushima current, which branches off from the main Kuroshio current.
In some Tōhoku areas, you’ll find patches of cultivated kelp and actual kelp forests in season (mostly between April and June), along with sandy seaweed environments, iconic endemic species such as squid (including the bigfin reef squid (Sepioteuthis lessoniana) and the Asian sheepshead wrasse (Semicossyphus reticulatus) and more seasonal species, along with a rich macro life (shrimps, crabs, nudibranchs, etc…).
Tōhoku’s Pacific coast is one of Japan’s major fishing grounds, as the warm waters of the Kuroshio collide with the cool waters of the Oyashio current just off its coastline, causing major seasonal plankton blooms.
Tōhoku’s marine ecosystem has always been one of the primary resources of the area, through fishing, of course, but also aquaculture, and the area was severely hit by the earthquake and tsunami that struck the Pacific coast on March 11, 2011.
Ever since disaster struck, dedicated volunteer divers have been in the water to recover and remove debris, and also to rehabilitate the local environment (recycling tsunamis debris into physical structures to provide shelter for marine life such as abalone and scallops and also restart edible kelp cultivation (konbu).
We would like to salute the outstanding efforts of a friend and former colleague of ours, Hiroshi Satō / Kuma-san, who has been actively involved in coordinating volunteer activities of underwater recovery, cleaning and environmental rehabilitation of his local Iwate waters, and has just celebrated 10th anniversary of this work in progress.
You can read more about the activities of the Sanriku Volunteer Divers here.
MAIN DIVING AREAS MENTIONED
Sea of Japan Coast
- The Oga Peninsula (Akita Prefecture) which offers relatively warm water due to the Tsushima current and impressive rock formations, and where it is possible to dive between June and October.
- Sado Island on the Sea of Japan side (Niigata Prefecture), which is the sixth-largest island of Japan in area following the four main islands and the main Island of Okinawa.
- Ryutoan-jima (Yotsushima), a small island of 800 metres off the coast of Yamagata Prefecture.
- Shonai area (Yamagata Prefecture)
- Tobishima, an island 40 km off the coast of Yamagata prefecture.
- The coast of the Tsugaru Peninsula (Aomori Prefecture), between the Sea of Japan and the Tsugaru Strait.
The Tsugaru Strait separates the islands of Honshū and Hokkaidō.
- Shizukawa, Onagawa Takeura (Miyagi Prefecture)
- The Sanriku coast (Aomori, Iwate and Miyagi Prefectures.)
DIVING HIGHLIGHTS AND ICONIC MARINE LIFE
It is possible to dive kelp forests environments in the spring months (April to June) around Sado island (Niigata Pref.).
The Asian sheepshead wrasse / Kobudai (Semicossyphus reticulatus) was made famous by a dedicated sequence in the film Oceans and, more recently in part one of BBC’s Blue Planet 2, which focused on their remarkable female to male transformation.
Kobudai wrasses can be easily be seen in Tōhoku between July and September on Sado Island (Niigata Pref.) and in Ryutoan-jima/Yotsushima (Yamagata Pref.).
Japanese banded houndshark (Triakis scyllium) are also often seen in the spring months, especially around the island of Tobishima (Yamagata Pref.).
SCHOOLING FISH AND PELAGICS
Tōhoku offers a good range of migratory pelagics and schooling fish, including schools of Pacific bluefin tuna (Thunnus orientalis) which are often seen in summer months at Shonai (Yamagata Pref.), juvenile Japanese amberjacks (Seriola quinqueradiata) (July to September, Shonai, Yamagata Pref. and October to December on Sado Island, Niigata Pref.) as well as schooling barracudas (Sphyraenidae) (summer months, Sado Island, Niigata Pref.).
SPAWNING EVENTS & AGGREGATIONS
Large aggregations of bigfin reef squid (Sepioteuthis lessoniana), an iconic Kuroshio/Tsushima current species, are often observed between the months of June and October in the Oga Peninsula (Akita Pref.) and around Sado Island (Niigata Pref.).
MACRO DIVING, ODD AND RARE CRITTERS
In the odd-looking, rare and macro critter category, Tōhoku offers the chance to dive with various deep-water creatures coming from the north, which are often spotted in the spring months in the Shonai area (Yamagata Pref.).
The weird looking smooth lumpsucker (Aptocyclus ventricosus), also found in Hokkaidō, can also be spotted in the early summer months around the Oga Peninsula (Akita Pref.) and between January to March on Sado Island (Niigata Pref.).
And the grunt sculpin or Grunt-fish (Rhamphocottus richardsonii), another definitely odd-looking critter, is one of the macro highlights of the area. It can be spotted in Japan at the Shizukawa port and Onagawa Takeura (Miyagi Pref.), and, more rarely, in Hokkaidō in winter, which is said to be the only places where they are found on this side of the Pacific.
Onagawa is Tōhoku’s most famous area for macro-diving,
For jellyfish lovers, the giant Nomura’s jellyfish (Nemopilema nomurai) is often found in the autumn months in Shonai (Yamagata Pref.).
Click here for more precise, detailed and practical information on diving in Tōhoku.