Frost formations bloom in Sounkyo tunnel

Frost flowers thickly covering the upper portion of the tunnel (Feb. 4, Sounkyo)

A magical gleam reflects off of the frost formations that thickly cover the rock surface of a lateral hole thought to have been dug over 70 years ago in the Sounkyo area of northern Hokkaido’s Kamikawa Town.

The tunnel interior has a high level of humidity and the small opening prevents wind from entering. Because of this, moisture in the tunnel air freezes, and frost formations grow larger little by little. The hole is thought to have been dug in the mid-1940s for a tunnel excavation bedrock survey. It is approximately 3 meters wide, 2 meters tall, and 30 meters deep. The frost formations thickly cover the rock surface near the entrance area.

The frost formations can be seen in the Sounkyo Visitor Center winter tour. Guide Sakuma Hiroshi explains, “Long frost formations are 10 centimeters and larger this season. They are definitely worth seeing.”


Sounkyo Visitor Center