Hokkaido (北海道 Hokkaidō, literally “Northern Sea Circuit”; Japanese pronunciation: [hokːaꜜidoː] ), 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.[1] 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. About 43 km north of Hokkaido lies Sakhalin Island, Russia. To its east and north-east are the disputed Kuril Islands.