Hokkaido (北海道, Hokkaidō, literally "Northern Sea Circuit"; Japanese pronunciation: [hokːaꜜidoː] (listen), Ainu: アィヌ・モシリ aynu mosir), 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 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.