Tsushima Strait

, also known as the Korea Strait, is a narrow body of water between Japan and South Korea. The name is used in two ways. It is used generally to describe the ocean area between Korea and Japan; and it also identifies the sea passage between the islands of Kyushu and Tsushima.
The strait links the East China Sea and the Sea of Japan in the northwest Pacific Ocean. Tsushima Island is between the western channel (Korea Strait) and the eastern channel (Tsushima Strait). 
Geography.
Depending on usage, the northern shore of the strait is the eastern coast of the Korean peninsula or it may mean the eastern coast of Tsushima. The southern shores of the strait are the western coasts of Kyūshū and Honshū. 
A warm current ("Tsushima-kairyū") runs through the straight from south to north.