Tsugaru Strait

The Tsugaru Strait (津軽海峡, Tsugaru Kaikyō) is a strait between Honshu and Hokkaido in northern Japan. It connects the Sea of Japan with the Pacific Ocean. The strait was named after the western part of Aomori Prefecture. The Seikan Tunnel passes under it at its narrowest point.

Japan's territorial waters extend only three nautical miles into the strait. This allows ships from other countries to pass through. The part of the strait in international waters is still within Japan's exclusive economic zone, and the Seikan Tunnel remains under Japanese control.

The Tsugaru Strait has two parts, both about 20 km across. Ferry services, such as the Tsugaru Kaikyō Ferry and the Seikan ferry, operate across the strait.

The strait is also important in nature. Thomas Blakiston, an English explorer, noticed that animals in Hokkaido are related to those in northern Asia, while those on Honshu are related to southern Asian species. This made the Tsugaru Strait a key boundary in animal geography, known as Blakiston's Line.