Japanese seas, straits and rivers, found on the map

Ten seas and straits, three rivers and one lake, which is the right proportion for a country made of islands. The shortest deck here, and every question on it is written. The rivers are short because the mountains are close to the coast, and the water that matters is the sea in between.

14 to find, 8 a run.

2 rounds, 6 of 8 to pass each. Pass one and its places are yours.

⚔️ Challenge someone to Japanese seas, straits and rivers

14 seas, straits and rivers · 3 groups

What the map tells you about each one

The paragraph the game shows when you find each one. Reading them first is not cheating.

Lakes1 on the map

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.

Rivers3 on the map

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.
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.

Seas and oceans10 on the map

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.
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.
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.
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.
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.
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.
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.
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.
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.
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.

Now find all 14 on the map

How this one works

How many seas, straits and rivers are on the map?

14. Every one of them is on the map, and a run asks 8 of them. Pass a round and the places you found in it drop out of the pool, so the next run is what you have left.

What is a round?

A run of 8 questions, and 6 right passes it. 2 rounds cover the whole map, and the counter at the top of the Japan page counts the ones behind you. Passing is what banks a round's finds: miss the mark and nothing is taken off the map, so every place that round asked about is still there to be asked again. A round is always the places you have not found yet, and when fewer than five are left it is topped up with a few you have found as review, so the last round is never one or two questions. Three quarters of it passes it.

Can I start the map over?

Yes. "Reset this map" under the counter puts all 14 back in the pool and sets the rounds to zero the moment you press it, so the whole map is there to be found again from nothing. It clears this map only; the other maps of Japan keep their progress.

Do I need an account?

No. The game plays in the page, and a guest's progress is kept in their own browser. Signing in carries it between devices and earns XP for a run.

What happens when I get one wrong?

The map names what you actually hit, then lights up the right answer in green and tells you something about the place. Missing one is how most of this map gets learned.

The other maps of Japan

Japanese prefectures47 to find Japanese cities47 to find

The same map for other countries

North America

Oceania

South America

All of Japan’s maps together on the Japan atlas page, the country itself on the Japan guide, and the other two hundred on the world map.