kaikyo

Kaikyo, written 海峡 and romanized as kaikyō (often anglicized as "kaikyo"), is the Japanese term for a strait or sea channel that connects two larger bodies of water and separates two landmasses. The characters literally mean "sea" and "strait." The term is widely used in geographic names across Japan to denote a narrow waterway between islands or peninsulas.

Geographically, kaikyō are important for navigation, weather, and marine ecosystems. They commonly form busy shipping lanes and influence local currents and tidal patterns. The presence of a kaikyō can affect climate along nearby coasts and the distribution of marine life in the surrounding waters. Many Japanese coastlines feature kaikyō that have given rise to notable engineering projects and transportation corridors.

Famous examples include Tsugaru Kaikyo (津軽海峡) between Honshu and Hokkaido; Kanmon Kaikyo (関門海峡) between Honshu and Kyushu; and Akashi Kaikyo (明石海峡) between Honshu and Awaji Island. Other named kaikyō include Soya Kaikyo (宗谷海峡) between Hokkaido and Sakhalin, and Tsushima Kaikyo (対馬海峡) near Tsushima Island, close to the Korean Peninsula. The Akashi Kaikyo Strait hosts the Akashi Kaikyō Bridge, one of the world’s longest suspension bridges, which connects Kobe with Awaji Island and serves as a major transport link.

In Japanese geography, kaikyō are distinguished from larger seas or bays and are central to maritime trade, fisheries, border regions, and regional infrastructure planning.