Japan's territorial waters extend to three nautical miles into the strait instead of the usual twelve, reportedly to allow nuclear-armed United States Navy warships and submarines to transit the strait without violating Japan's prohibition against nuclear weapons in its territory.
The Tsugaru Strait has eastern and western necks, both approximately 20 km across with maximum depths of 200 m and 140 m respectively.
In the past, the most common way for passengers and freight to cross the strait was on ferries, approximately a four-hour journey.
On September 26, 1954, 1,172 lives were lost when the ferry Tōya Maru sank in the strait.
Thomas Blakiston, an English explorer and naturalist, noticed that animals in Hokkaido were related to northern Asian species, whereas those on Honshu to the south were related to those from southern Asia. The Tsugaru Strait was therefore established as a major zoogeographical boundary, and became known as the "Blakiston Line".