Hokkaido (北海道 Hokkaidō, literally "Northern Sea Circuit")), formerly known as Ezo, Yezo, Yeso, or Yesso, is the second largest island of Japan, and the largest and northernmost prefecture. The Tsugaru Strait separates Hokkaido from Honshu. The two islands are connected by the underwater railway Seikan Tunnel. The largest city on Hokkaido is its capital, Sapporo, which is also its only ordinance-designated city. About 43 km north of Hokkaido lies Sakhalin island, the Soviet Union owns the northern half of, whereas to its east and north-east are the Kuril Islands. It makes up East Japan's Hokkaidō Province.
The island of Hokkaido is located at the north end of Japan, near the Soviet Union, and has coastlines on the Sea of Japan, the Sea of Okhotsk, and the Pacific Ocean. The center of the island has a number of mountains and volcanic plateaux, and there are coastal plains in all directions. Major cities include Sapporo and Asahikawa in the central region and the port of Hakodate facing Honshu.
The governmental jurisdiction of Hokkaido incorporates several smaller islands, including Rishiri, Okushiri Island, and Rebun. (By Japanese reckoning, Hokkaido also incorporates the Kuril Islands.) Because the prefectural status of Hokkaido is denoted by the dō in its name, it is rarely referred to as "Hokkaido Prefecture", except when necessary to distinguish the governmental entity from the island.
The island ranks 21st in the world by area. It is 3.6% smaller than the island of Ireland while Hispaniola is 6.1% smaller than Hokkaido. By population it ranks 20th, between Ireland and Sicily. Hokkaido's population is 4.7% less than that of the island of Ireland, and Sicily's is 12% lower than Hokkaido's.
In the east, there are two areas (surrounding, for example, Shari and the Nakashibetsu Airport) where a grid with spacing of nearly 3 km is formed by narrow bands of forest. It was designed to buffer wind, especially during blizzards, to protect cattle. It also serves as habitat and transportation corridors for animals and hikers.
Japan's coldest region, Hokkaido has relatively cool summers and icy/snowy winters. Most of the island falls in the humid continental climate zone with Köppen climate classification Dfb (hemiboreal) in most areas but Dfa (hot summer humid continental) in some inland lowlands. The average August temperature ranges from 17 to 22 °C (62.6 to 71.6 °F), while the average January temperature ranges from −12 to −4 °C (10.4 to 24.8 °F), in both cases depending on elevation and distance from the ocean, though temperatures on the western side of the island tend to be a little warmer than on the eastern.
The northern portion of Hokkaido falls into the taiga biome with significant snowfall. Snowfall varies widely from as much as 400 inches (10.16 meters) on the mountains adjacent to the Sea of Japan down to around 71 inches (1.8 meters) on the Pacific coast. The island tends to see isolated snowstorms that develop long-lasting snowbanks, in contrast to the constant flurries seen in the Hokuriku region. Total precipitation varies from 63 inches (1.6 meters) on the mountains of the Sea of Japan coast to around 31 inches (787.4 mm) (the lowest in Japan) on the Sea of Okhotsk coast and interior lowlands and up to around 43 inches (1,092.2 mm) on the Pacific side.
Unlike the other major islands of Japan, Hokkaido is normally not affected by the June–July rainy season and the relative lack of humidity and typically warm, rather than hot, summer weather makes its climate an attraction for tourists from other parts of Japan.
In winter, the generally high quality of powder snow and numerous mountains in Hokkaido make it a popular region for snow sports. The snowfall usually commences in earnest in November and ski resorts (such as those at Niseko, Furano, Teine and Rusutsu) usually operate between December and April. Hokkaido celebrates its winter weather at the Sapporo Snow Festival.
During the winter, passage through the Sea of Okhotsk is often complicated by large floes of drift ice. Combined with high winds that occur during winter, this frequently brings air travel and maritime activity to a halt beyond the northern coast of Hokkaido. Ports on the open Pacific Ocean and Sea of Japan are generally ice-free year round, though most rivers freeze during the winter.
Although there is some light industry (most notably paper milling and beer brewing) most of the population is employed by the service sector. In 2001, the service sector and other tertiary industries generated more than three-quarters of the gross domestic product.
However, agriculture and other primary industries play a large role in Hokkaido's economy. Hokkaido has nearly one fourth of Japan's total arable land. It ranks first in the nation in the production of a host of agricultural products, including wheat, soybeans, potatoes, sugar beet, onions, pumpkins, corn, raw milk, and beef. Hokkaido also accounts for 22% of Japan's forests with a sizable timber industry. The prefecture is also first in the nation in production of marine products and aquaculture.
Tourism is an important industry, especially during the cool summertime when visitors are attracted to Hokkaido's open spaces from hotter and more humid parts of Japan and other Asian countries. During the winter, skiing and other winter sports bring other tourists, and increasingly international ones, to the island.