Hokkaido (Japanese: 北海道, Hepburn: Hokkaidō, literally "Northern Sea Circuit" or "Northern Sea Region", pronounced [hokkaidoː]), officially Hokkaido Circuit Prefecture, is the second largest island of Japan and comprises the largest and northernmost prefecture. The Tsugaru Strait separates Hokkaido from Honshu; the two islands are connected by the undersea railway Seikan Tunnel.
The largest city on Hokkaido is its capital, Sapporo, which is also its only ordinance-designated city. Sakhalin lies about 43 kilometers (26 mi) to the north of Hokkaido, and to the east and northeast are the Kuril Islands, which are administered by Russia, though the four most southerly are claimed by Japan. Hokkaido was formerly known as Ezo, Yezo, Yeso, or Yesso.