Japan is an island arc off the east coast of Asia, stretching more than 3,000 km from the Sea of Okhotsk to the Philippine Sea and covering 377,974 km² spread over 14,125 islands, of which Honshu, Hokkaido, Kyushu, Shikoku and Okinawa are the largest. About 73% of the land is mountainous, so its 123 million people (2025) crowd onto coastal plains such as the 17,000 km² Kantō Plain around Tokyo. The highest point is Mount Fuji at 3,776 m, the longest river is the Shinano at 367 km, the largest lake is Lake Biwa at 670 km², and the lowest natural point is Hachirōgata in Akita, 4 m below sea level.
Because no spot in Japan is more than 150 km from the sea, the whole country can be read as a single slope: from volcanic summits and granite ridges, down steep rivers, across small crowded plains, into lakes and reclaimed lagoons, and then over the edge of one of the deepest ocean trenches on Earth. The descent below follows that order, from the top of Fuji to the floor of the Japan Trench.
Mount Fuji at 3,776 m: a Volcano Last Active in 1707
The summit of Japan is the crater rim of Mount Fuji, measured at 3,776.24 m, on the border of Shizuoka and Yamanashi prefectures about 100 km south-west of Tokyo. It is an active stratovolcano with an unusually symmetrical cone, snow-covered for about five months of the year and visible from the capital on clear days. It last erupted in 1707–1708, the Hōei eruption, which opened a new crater and a second peak, Mount Hōei, on the south-eastern flank and dropped cinders and ash as far as Musashi province, around modern Tokyo. An earlier eruption in 864 CE laid down the lava field on the north-west flank that is now covered by Aokigahara, a dense forest growing on about 30 km² of hardened lava.
Fuji is one of 108 active volcanoes in Japan, about a tenth of the world’s total. They exist because the archipelago sits where the Pacific, Philippine Sea, Okhotsk and Eurasian or Amurian plates meet. Fuji itself stands on a triple junction where the Eurasian, North American and Philippine Sea plates meet, with the Pacific Plate sinking beneath all three. UNESCO added it to the World Heritage List as a cultural site on 22 June 2013, citing centuries of pilgrimage and art; 25 locations around the mountain, including the Fujisan Hongū Sengen Taisha shrine, are included. For the eruption history and hazards in more depth, see our guide to Mount Fuji as a volcano.
Kita-dake, Okuhotaka and Yari-ga-take: the Alps Above 3,000 m
The next rung down is not a volcano at all. Central Honshu is crossed by three parallel ranges that together form the Japanese Alps: the Hida Mountains (Northern Alps), the Kiso Mountains (Central Alps) and the Akaishi Mountains (Southern Alps). Several peaks pass 3,000 m. Second only to Fuji is Kita-dake, 3,193 m, in the Akaishi range in Yamanashi Prefecture, known as “the leader of the Southern Alps”, with a 600 m rock face called the Kitadake Buttress on its eastern side. Third is Okuhotaka, 3,190 m, the highest peak of the Hotaka group on the border of Nagano and Gifu prefectures in the Hida range.
North along the Hida crest from the Hotaka peaks stands Yari-ga-take, 3,180 m, whose sharp summit gives it its name, “spear peak”, and the nickname “Matterhorn of Japan”. The Buddhist priest Banryū made the first recorded ascent on 28 July 1828, and the English clergyman Walter Weston climbed it in 1891; Weston did much to popularise mountaineering in Japan. The Kiso range in between is built of granite; the Kiso River drains it south to Ise Bay, while the Tenryū, flowing out of Lake Suwa, cuts between the Central and Southern Alps to the Enshū Sea. On the Pacific side of Japan’s spine the mountains are steep, 1,500 to 3,000 m, and cut by deep gorges. The Sea of Japan side is lower, with plateaus and ranges of 500 to 1,500 m.
Down the Azusa and Shinano Rivers to the Echigo Plain
Water from Yari-ga-take feeds the Azusa River, one of the headwaters of the Shinano, Japan’s longest river. As the Sai it flows past Matsumoto to meet the Chikuma, the name the Shinano carries in its upper reaches, at Nagano; the Chikuma itself rises near Mount Kobushi. The joined river turns north-east into Niigata Prefecture and out to the Sea of Japan, 367 km in all. Like most Japanese rivers it is short and steep by world standards, fast enough to be valuable for hydroelectric power but navigable only near its mouth.
Near the coast the Shinano and the Agano have filled an old lagoon with sediment to build the Echigo Plain, about 2,000 km² of flat ground that is now the largest rice-growing area in Japan. Diversion channels cut to protect Niigata from floods carried the sediment away from the old river mouth, and between 1947 and 1975 the shore near the city retreated as a result. Niigata’s winters show the other side of this coast: north-west winds crossing the Sea of Japan pick up moisture and bring heavy snowfall to the mountains facing the Sea of Japan, while the Pacific side stays clear, a pattern covered in our guide to the climate of Japan.
From Mount Ōminakami to Chōshi: the Tone River and the Kantō Plain
On the Pacific side, the Tone River starts at Mount Ōminakami, 1,831 m, in the Echigo Mountains on the Gunma–Niigata border, and runs 322 km to the ocean at Chōshi in Chiba Prefecture. It is the second-longest river in Japan but drains the largest basin, 16,840 km², and its old nickname Bandō Tarō, “eldest son of the east”, reflects its standing. The land it crosses is the Kantō Plain, the largest in the country at 17,000 km², covering more than half the Kantō region across Tokyo, Saitama, Kanagawa, Chiba, Gunma, Tochigi and Ibaraki prefectures.
Mountains wall the plain on the north and west, and it opens east to the Pacific at Kujūkuri Beach and south to Tokyo Bay and Sagami Bay. Because it was the largest flat, farmable area in central Japan, it became the power base of the Tokugawa shogunate, which set up in Edo in 1603. Edo became Tokyo in 1868, and Greater Tokyo is now one of the three most populous metropolitan areas in the world, with about 37 million people by a 2026 UN estimate. The chart shows how exceptional the Kantō Plain is: every other plain in Japan is a fraction of its size.
The two other big lowlands of Honshu are much smaller: the Nōbi Plain around Nagoya, fed by the Kiso River, and the Osaka Plain, which connects inland to the Kyoto and Nara basins. Hokkaido has more open ground than Honshu’s mountainous interior, with the Ishikari and Tokachi plains and the Kushiro Plain, Japan’s largest wetland.
Lake Biwa, 104 m Deep in a Four-Million-Year-Old Basin
North-east of Kyoto, in Shiga Prefecture, lies the country’s largest freshwater lake. Lake Biwa covers 670.3 km² and reaches 104 m deep. It fills a basin opened by plate movement in an active rift zone, and it has held water for at least 4 million years, which makes it one of the oldest lakes in the world, estimated at 13th. That age explains its biology: more than 1,000 species and subspecies live in it, and of its 46 native fish, 11 species and 5 subspecies are found only in or near the lake. About 5,000 water birds visit each year. Its main outlet, the Seta River, becomes the Uji and then joins other rivers as the Yodo before reaching Osaka Bay, and the lake supplies drinking water to about 15 million people in the Kansai region.
Hachirōgata, 4 m Below Sea Level in Akita
Japan’s lowest natural point is on the Sea of Japan coast of northern Honshu. Hachirōgata, a lagoon in Akita Prefecture, lies about 4 m below sea level. Until the 1950s it was the second-largest lake in the country after Biwa. Reclamation began in 1957 to create new rice land; the village of Ōgata was founded on the drained lakebed on 1 October 1964, and by 1977 some 172 km² had been reclaimed. What remains of the lake covers only 48.3 km².
Hachirōgata is the extreme case of a national habit. Because flat land is so scarce, about 0.5% of Japan’s area is reclaimed land, and most of the country’s tidal flats have been filled in since the Second World War. Kansai International Airport, on an artificial island in Osaka Bay, and Kobe’s Port Island are built this way. The rice surplus that followed soon after Hachirōgata was drained has led some to call the project a mistake, and others regret the lost wetland; the once-thriving shijimi clam fishery declined as the lake became less brackish.
Beyond the Coast: the Japan Trench off Tōhoku
The descent does not end at the shoreline. East of Honshu and Hokkaido the Pacific Plate dives beneath the Okhotsk Plate at the Japan Trench, moving about 7.9 to 9.2 cm a year. The trench runs about 800 km and reaches 8,046 m at its deepest, and further south the Izu–Ogasawara Trench reaches about 9,810 m. From the top of Fuji to the floor of these trenches is a drop of more than 13 km within a few hundred kilometres. The same subduction raises the volcanoes and drives the earthquakes: the megathrust Tōhoku earthquake of 11 March 2011 moved parts of north-eastern Japan 2.4 m closer to North America and dropped a 400 km stretch of coastline by about 0.6 m, letting the tsunami run further inland.
On the other side of the islands, the Sea of Japan is a back-arc basin that opened about 15 million years ago as the arc was pulled away from the Asian mainland; it reaches 3,742 m at its deepest. That opening is what turned a strip of the continental edge into an archipelago in the first place, and it is why Japan’s landscape runs so quickly from snowfields to seabed. For quick figures on islands, coastline and extremes, our list of facts about Japan’s geography gathers them in one place.