Japanese seas, straits and rivers, found on the map

Every one on the map

Every place listed below can be asked in this game. Places you find in a passed round drop out of your remaining pool. Grouped into 8 learning regions, matching the rounds on the Japan guide. Regions with no places in this map’s selection are omitted. Shared rivers and seas appear in one learning group, even when they cross regional boundaries.

What the map tells you about each one

The paragraph the game shows when you find a place, for all 14 of the ones written by hand. Reading them first is not cheating.

Sea of Japan

It is nearly a closed sea: the four straits into it are all shallow and narrow, so it barely exchanges water with the Pacific and its depths are almost still. The cold winter wind off Siberia crosses it, picks up moisture and drops it as snow on the Japanese coast, which is why one side of the country is buried every winter and the other is not.

Pacific Ocean

The Japan Trench runs about 200 kilometers offshore and reaches roughly 8,000 meters down, where the Pacific plate slides under the one Japan sits on at about 8 centimeters a year. That is where the 2011 earthquake happened, and it moved the coast of Honshu something like 2.4 meters east.

Seto Inland Sea

The inland sea is about 450 kilometers long, nowhere very deep, and holds around 700 islands. It was the main road between western and eastern Japan for most of the country’s history, and it became its first national park in 1934. Three separate bridge routes now cross it, the longest of them about 13 kilometers.

Sea of Okhotsk

Drift ice comes down this sea from the Amur estuary and reaches the Hokkaido coast most years between late January and March, which is the lowest latitude sea ice gets to anywhere in the northern hemisphere. The Amur’s fresh water is what makes the surface layer thin and salt-poor enough to freeze.

East China Sea

The Kuroshio, the Pacific’s equivalent of the Gulf Stream, comes north through this sea at up to four knots and then turns east along Japan’s southern coast, which is what keeps the winters on that side mild. Most of the sea is continental shelf under 200 meters deep.

Philippine Sea

The Philippine Sea Plate goes under southwestern Japan along the Nankai Trough, and the great earthquakes that come off it have arrived roughly every hundred to two hundred years for as long as records exist. The last pair were in 1944 and 1946, which is why Japan plans for the next one in some detail.

Korea Strait

The strait is about 200 kilometers wide with the island of Tsushima in the middle of it, which splits it in two. The Russian Baltic Fleet arrived here in May 1905 after sailing 33,000 kilometers around the world and was destroyed in an afternoon, which was the first time an Asian power had beaten a European one at sea.

Tsugaru Strait

The strait is about 20 kilometers across at its narrowest and deep enough that it stayed open when sea levels fell in the ice ages, which is why the animals north of it are Siberian and the ones south of it are Asian. The line runs through the water and is named after Thomas Blakiston, who noticed it in the 1880s.

La Pérouse Strait

It is about 42 kilometers wide and separates Hokkaido from Sakhalin, which makes it Japan’s northern edge. It is named for the French navigator who charted it in 1787 and disappeared with both his ships in the Pacific the following year. The Japanese call it the Sōya Strait, after the cape on their side.

Uchiura Bay

The bay is almost a circle about 50 kilometers across, which is why its other name is Funka Bay, the bay of eruption: the shape is volcanic, and the active cone of Usu stands on its southern rim and has erupted four times since 1900. Scallops farmed in it are a large part of the Japanese supply.

Lake Biwa

Biwa is the largest lake in Japan at about 670 square kilometers and one of the oldest in the world, at something like four million years, which has given it around sixty species that live nowhere else. It supplies drinking water to roughly 14 million people downstream, Kyoto and Osaka among them.

Tone

The Tone drains the largest basin in Japan and is the second longest river at about 322 kilometers. It used to empty into Tokyo Bay; the Tokugawa spent sixty years from 1594 digging it a new course east to the Pacific, to protect Edo from its floods and to open a barge route to the north.

Ishikari

The Ishikari is about 268 kilometers long, the longest river on Hokkaido and the third longest in the country. Sapporo sits on the plain it built. Straightening it in the twentieth century cut roughly 60 kilometers off its length and left a line of oxbow lakes along the old bends.

Mogami

The Mogami is about 229 kilometers long and is the only major river in Japan that stays inside a single prefecture the whole way. It was the safflower and rice route out of the interior. Bashō came down it by boat in 1689 and left the haiku about it that Japanese schoolchildren still learn.

How this one works

The other maps of Japan

Sweden has the same map in Swedish waters. Denmark has the same map in Danish waters. India has the same map in Indian waters. Mexico has the same map in Mexican waters. United States has the same map in American waters. China has the same map in Chinese waters. Turkey has the same map in Turkish waters. France has the same map in French waters. Germany has the same map in German waters. Spain has the same map in Spanish waters. Brazil has the same map in Brazilian waters. United Kingdom has the same map in British waters. Italy has the same map in Italian waters. South Korea has the same map in Korean waters. All three together on the Japan atlas page, the country itself on the Japan guide, and the other two hundred on the world map.