Japan, a country of islands, extends along the eastern or Pacific coast of Asia. The main islands, running from north to south, are Hokkaido, Honshu (or the mainland), Shikoku, and Kyushu. Naha in the Ryukyu archipelago is over 600 kilometres (375 mi) to the southwest of Kyushu. In addition, about 3,000 smaller islands may be counted in the full extent of the archipelago.
Japan is the 18th most densely populated country in the world. About 73% of the country is mountainous, and unsuitable for agricultural, industrial, or residential use, due to the generally steep elevations, climate, and risk of landslides caused by earthquakes, soft ground, and heavy rain. This has resulted in an extremely high population density in the habitable zones that are mainly located in coastal areas.
Its location on the Pacific Ring of Fire, at the juncture of three tectonic plates, gives Japan frequent low-intensity earth tremors and occasional volcanic activity. Destructive earthquakes, often resulting in tsunamis, occur several times each century. The most recent major quakes include the 2004 Chuetsu Earthquake and the Great Hanshin Earthquake of 1995. Hot springs are numerous, and have been developed as resorts.
The main rainy season begins in early May in Okinawa, and the stationary rain front responsible for this gradually works its way north until it dissipates in northern Japan before reaching Hokkaido in late July. In most of Honshu, the rainy season begins before the middle of June and lasts about six weeks. In late summer and early autumn, typhoons often bring heavy rain.
Japan is home to nine forest ecoregions which reflect the climate and geography of the islands. They range from subtropical moist broadleaf forests in the Ryukyu and Bonin islands, to temperate broadleaf and mixed forests in the mild climate regions of the main islands, to temperate coniferous forests in the cold, winter portions of the northern islands.