The UN Seahorse in Japan!
Commemorating the Year of the Ocean
Oceans around Japan

View of the Japan islands
from space

More information:

Japan's Basic Environmental Plan
Conservation of Marine Animals
Effect of Sea-level Rise on Japan
Oceans, Coasts and Small Islands
The Sea of Okhotsk is to the north of the four main islands of Japan, the Pacific Ocean is to the east and south, the East China Sea is to the southwest, and the Korea Strait and the Sea of Japan are on the west. On the Asian continent, Russia is to the north and northwest of Japan, and North Korea, South Korea, and China are to the west. Further south, Taiwan lies to the west of Japanís Ryukyu Islands.

| Japan Sea | Okhotsk Sea | Pacific Ocean |

With more than 1,000 islands comprising the archipelago, it has a coastline of 34,390 kms. The coastline is a combination of steep cliffs and beaches. Long a sea-faring society, Japan has a food self-sufficiency of only 50%, but boasts the world's largest fish catch of more than 10 million metric tons per annum (1991 figures).

The Japan islands lie at the point where three tectonic plates meet - the Eurasian plate, the Pacific plate and the Philippine plate. The friction and movements between these three plates makes Japan highly susceptible to earthquakes and consequent tsunamis (or tidal waves). The Great Hanshin earthquake that struck Kobe recently is an example of this vulnerability.

On the Pacific side of Japan, the continental shelves cover an average distance of 200 kms before plunging more than 6,000 meters (9,000 to 10,000 meters in the trenches) in the deep sea area. There are three important trenches in the area - Kuril Trench to the north, Japan Trench off Tokyo, and Izu-Bonin Trench towards the south. Another trench, the Nansei Shoto Trench runs between Okinawa and Taiwan further south. Trenches, found in the lowest parts of the earth's surface, are formed by the subduction of one plate below the edge of another, causing major earthquakes periodically.

The meeting of plates and trenches also produces an interesting set of ocean floor phenomena, such as thermal vents (which support a peculiar set of lifeforms, some of which can survive in temperatures as high as 90 degC!), hydrothermal deposits, ocean currents etc. Trenches have also been a focus of interest for earthquake prediction.

In general, ocean research in Japan has focussed on several issues:

Ocean Systems:
The heat capacity of the ocean is approximately 1000 times more than the atmosphere. The ocean transports heat with its current, supplies energy to the atmosphere, dissolves various substances to create chemical reactions, and supports a large variety of lifeforms, playing a dominant role in stabilizing global environment and maintaining life on the planet. Ocean currents therefore play a key role in distributing the heat.

Atmospheric Systems:
The atmosphere also plays an important role in the circulation of heat and momentum in the wind, water, CO2 etc. There is little data of the atmosphere above oceans, which is critical for the analyses of meteorological phenomena. The role that oceans play in the motion of the atmosphere as sources of water and heat is predominant. This understanding is indispensable for meteorology and climatology.

Snow/Ice Systems:
Since snow and ice have high albedo (reflectivity against solar radiation), and they occupy large areas of earth's surface, they have a significant effect on the global flow of water and heat, exerting a great influence on meteorology and climate.

Besides the above issues, research and development have also focussed on biological systems in oceans - as a source of food, as a study of habitats and eco-systems, and in understanding land/surface phenomena. Coastal area management has also been another key focus of research.

A hydrothermal vent at 1400 m depth (JAMSTEC)

A hydrothermal vent at 1400 m depthThe applications of marine and deep sea research work has been seen in several fields including basic research (origins and evolution of life, genetic engineering ... ); conservation of the environment (cleaning of coastal areas, waste water disposal ... ); climate study (agriculture, fishing ... ); industries (electronics, energy, chemical industry ... ) and medicine (bio-active materials, medicine ... ).

A considerable amount of data collation, analysis and packaging is taking place in many institutions - research on ocean floors, marine and deep sea lifeforms, ocean surfaces and currents, climate change, coastal areas, marine transportation, ports and harbours etc. A list of institutions engaged in such research is included.

| Japan Sea | Okhotsk Sea | Pacific Ocean |


Japan Sea

A marginal sea of the western Pacific Ocean bounded on the east by the Japanese islands, the west and southwest by Korea, and the north and northwest by the former Soviet Union. It is connected to the East China Sea in the south, the Okhotsk Sea in the north, and the Pacific Ocean in the east via narrow passages whose sill depths don't exceed 100 m. It comprises the Japan Basin (with depths exceeding 3500 m) north of about 40 N, and the Yamato Basin (with depths around 2500 m) south of 40 N, the the basins separated by the Yamato Ridge. The area is 978,000 km2, the average depth 1750 m, and the greatest depth about 4050 m.

Prominent circulation features in the Japan Sea include the Tshushima Current, the Tsugaru Current, the Liman Current, the North Korea Current and the Mid-Japan Sea or Maritime Province Current. Water masses found there include Japan Sea Middle Water (or Intermediate Water) and Japan Sea Proper Water.

The Japan Sea is a meeting place for warm currents from the south and cold currents from the north, with the confluence being the Polar Front.


Okhotsk Sea

A marginal sea on the northern rim of the Pacific Ocean centered near 55 N and 150 E. It is bounded by the Siberian coast to the west and north, the Kamchatka Peninsula to the east, and the Kurile Islands to the south and southeast. It covers an area of about 1,600,000 km, has an average depth of about 860 m, and a maximum depth of 3370 m in the Kurile Basin. It is connected to both the Pacific Ocean and the Japan Sea via narrow passages, the most important ones being (for the former) the Boussole Strait (2318 m) and the Kruzenshtern Strait (1920 m) and (for the latter) the Tatarskyi Strait (50 m) and the Soya (or La Perouse) Strait (200 m).

The prominent surface circulation feature is the Soya Current, an extension of the Tsushima Current that flows through the southern part of the Okhotsk Sea. The current shear between this and the more quiescent offshore waters frequently eddies of around 10-50 km diameter.


Pacific Ocean

The world's largest geographic feature, the Pacific Ocean covers more than 166 million square kilometers (more than 64 million square miles) - about one-third of the earth's surface. The area of the Pacific is greater than that of all of the continents combined, and it makes up nearly half of the area covered by the earth's oceans.

The most significant surface currents of the Pacific are the cyclonic subpolar gyre in the north, the anticyclonic North Pacific subtropical gyre, the narrow and cyclonic northern tropical cell including the (NECC) North Equatorial Counter current, the westward South Equatorial Current (SEC) at the equator and to the south, the anticyclonic South Pacific subtropical gyre, and the Antarctic Circumpolar Current (ACC).


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