The pilot shaft of the Seikan Tunnel, the world's longest sub-aqueous tunnel (53.85 km) between the Japanese islands of Honshū and Hokkaidō, breaks through.

The Seikan Tunnel is a 53.85-kilometre (33.5-mile) dual-gauge railway tunnel in Japan, with a 23.3-kilometre (14.5-mile) segment running beneath the seabed of the Tsugaru Strait, which separates Aomori Prefecture on Honshu, Japan's main island, from the northern island of Hokkaido. The tunnel's track level lies approximately 100 metres (330 ft) below the seabed and 240 metres (790 ft) below sea level. Following several decades of planning and construction, the tunnel opened on 13 March 1988.

Honshu , historically known as Akitsushima , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the seventh-largest island in the world, and the second-most populous after the Indonesian island of Java.

Hokkaido is the second-largest island of Japan. Together with its surrounding islands, it comprises the largest and northernmost prefecture, making up its own region. The Tsugaru Strait separates Hokkaidō from Honshu; the two islands are connected by railway via the Seikan Tunnel.

January 27 is the 27th day of the year in the Gregorian calendar; 338 days remain until the end of the year.