Japan Geography, Climate & Nature

Japan comprises 14,125 islands along the Pacific coast of Asia, stretching over 3,000 kilometres north-east to south-west from the Sea of Okhotsk to the East China Sea. The five main islands, north to south, are Hokkaido, Honshu, Shikoku, Kyushu and Okinawa; the Ryukyu Islands, Okinawa among them, form a chain south of Kyushu, and the Nanpō Islands lie south and east of the main group. Total territory is 377,975 square kilometres, and the coastline — 29,751 kilometres, the sixth longest in the world — is long out of all proportion to the land, which is why the far-flung outlying islands give Japan such a large exclusive economic zone.

Why the cities are so dense

The archipelago is 67 per cent forest and 14 per cent agricultural. The terrain is primarily rugged and mountainous and is restricted for habitation, so the habitable zones — mainly coastal — carry very high densities. Honshu holds 450 people per square kilometre; Hokkaido, the least dense, holds 64.5. Around 0.5 per cent of the total area is umetatechi, land reclaimed from the sea. That is the whole explanation for how Japanese cities look and feel.

The Ring of Fire

Japan is substantially prone to earthquakes, tsunami and volcanic eruption because of its position on the Pacific Ring of Fire, and it has 111 active volcanoes. It ranked 17th for natural disaster risk in the 2016 World Risk Index. Destructive earthquakes, often producing tsunami, occur several times each century: the 1923 Tokyo earthquake killed over 140,000, and the 1995 Great Hanshin and 2011 Tōhoku earthquakes are the most recent major ones. Mount Fuji on the Pacific coast of central Honshu is the highest peak and itself an active volcano, and the same geology gives Japan its onsen.

Water

Lake Biwa is an ancient lake and the country's largest freshwater body.

North and south

Hokkaido, the northernmost island, is cooler and sparsely populated. Okinawa, far to the south, is a subtropical chain with a distinct Ryukyuan culture — and, being its own main island rather than part of Kyushu, is a region in its own right.

Japan's long north-south stretch — over 3,000 kilometres from the Sea of Okhotsk to the East China Sea — gives it real climate variation. Hokkaido in the north has cold, snowy winters; Okinawa in the far south stays subtropical year-round.

Four seasons, and a fifth

Most of the country has four distinct seasons — a rainy season (tsuyu) in June, a hot summer, a mild autumn, and a cold but generally dry winter. Summer heat and humidity are severe, and heatstroke is a real risk in July and August.

Typhoons

The tropical cyclone season runs June to December, peaking between July and September, with the highest risk in the southern parts of the country. Typhoons often arrive with damaging high tides, raising the risk of landslides and flooding — and the danger increases when an earthquake occurs shortly after a storm has saturated an area, which is a compounding risk particular to Japan. Monitor Japan Meteorological Agency forecasts and follow evacuation orders.

Heavy rain outside the storms

Periods of heavy rainfall are common in both the rainy and typhoon seasons. Intense rain leads to flooding, landslides and significant disruption to transport and infrastructure, and conditions can worsen rapidly with little warning, especially in low-lying and coastal areas.

The snow coast

Areas facing the Sea of Japan receive some of the heaviest snowfall anywhere on Earth in winter — the same phenomenon that makes the ski resorts famous for exceptionally light powder.

The archipelago is 67 per cent forest and 14 per cent agricultural, and that ratio is the single most important fact about Japanese land. The terrain is primarily rugged and mountainous and is restricted for habitation, so the habitable coastal zones carry very high densities: Honshu holds 450 people per square kilometre and Hokkaido 64.5. About 0.5 per cent of the total area is reclaimed land.

Blakiston’s Line

Japan has its own biogeographic boundary, and it is worth knowing about before you cross it. North of Blakiston’s Line the species are subarctic, having colonised Japan from the north. South of it, in the Ryukyus, they are south-east Asian and tropical. Between the two lies a temperate zone sharing many species with China and Korea. The islands stretch a long way north to south across a wide range of climatic zones, which is why isolation from the Asian mainland has produced high diversity rather than poverty, and a great many endemic species found nowhere else.

What the numbers look like

Around 4,000 to 6,000 plant species occur naturally, in vegetation running from subtropical forest in the south to coniferous forest in the north: mangroves, cycads and tree ferns in the subtropics; broad-leaved evergreen forest with many oaks in warm-temperate Kyūshū, Shikoku and south-western Honshu; broad-leaved deciduous beech and jolcham oak in north Honshu and south-west Hokkaido; conifers dominant across much of Hokkaido and the central mountains. Bamboo grows in 400 to 500 species, from the dwarf sasa to take reaching twenty metres. Japanese red cedar, Cryptomeria japonica, is the tallest conifer at forty metres — and conifer plantations have replaced natural forest in many areas, which is the caveat to the 67 per cent.

Protection, and a rule for visitors

Japan passed a forest protection law in 1897 — for erosion control, river sources and fish ecosystems — and as of 2023 12 million hectares are protected. Some fishermen have maintained coastal forest deliberately, and the coastal waters below have greater fish biodiversity as a result. The Ministry of the Environment runs hunting restrictions, captive breeding and habitat restoration.

The part that concerns a visitor directly: feeding wild animals — esayari — has led local governments to issue fines and other measures, because it makes animals dependent. The macaques will come to you; do not hand them anything.

Volcanic ground

Japan sits on the Pacific Ring of Fire and has 111 active volcanoes. Destructive earthquakes, often bringing tsunami, occur several times each century. The consequence for habitat is constant disturbance and renewal — and for visitors, the onsen.

About 130 species of land mammal occur in Japan. The largest are the two bears: the Ussuri brown bear, the largest land animal in the country, in Hokkaido, where it holds an important place in Ainu culture; and the Asian black bear in the mountains of Honshu, Kyūshū and Shikoku. Smaller carnivores include the red fox, the Japanese raccoon dog — the tanuki — and the Japanese marten. There are two wild cats: the leopard cat on Tsushima, and the Iriomote cat, which lives on one small island and nowhere else.

The world’s most northerly monkey

The Japanese macaque is the country’s most famous mammal and the most northerly monkey in the world — the reason the images of monkeys sitting in snow-covered hot springs exist at all. Grazing mammals include the sika deer, the Japanese serow and the Japanese boar. Offshore are sea otter, dugong, finless porpoise and Steller’s sea lion.

What has gone

Japan had two wolves and lost both: the Hokkaido wolf went extinct in 1889 and the Honshū wolf in 1905. Further back, the archipelago carried the elephant Palaeoloxodon naumanni, the giant deer Sinomegaceros yabei and cave lions. The wolves are recent enough that their absence still shapes the deer population.

Birds, reptiles, amphibians

Over 600 bird species have been recorded and more than 250 breed here, several of them endemic — the Japanese woodpecker, the copper pheasant, and the green pheasant, the national bird. Large numbers migrate through in spring and autumn, and in winter several sites matter for swans, geese and cranes. There are about 73 reptile species, nearly half of them endemic, with sea turtles and highly venomous but non-aggressive sea snakes in the warmer southern waters, and the habu pit vipers, many of them endemic to the warmer Ryukyu islands, while the mamushi is the one found on the main islands. Of over 40 amphibians, the Japanese giant salamander is one of the largest amphibians in the world.

Water and insects

Over 3,000 kinds of fish have been recorded. Coral reefs in the Ryukyus hold parrotfish and anemonefish; the deep water off Japan has produced the goblin shark and the frilled shark. There are around 300 butterflies and 190 dragonflies, including the primitive Epiophlebia superstes, plus cicadas, crickets, the Asian giant hornet and fireflies — firefly viewing is a genuine tourist season in some areas.

Two practical notes

Do not feed the animals. Esayari has led local governments to issue fines, because habituated animals stop foraging. And the mosquitoes that carry dengue bite during the daytime, particularly around sunrise and sunset — the opposite of the pattern most travellers plan for.