Abukuma-do

Abukuma-dō (あぶくま洞 - Abukuma Cave) is a limestone cave located in Fukushima Prefecture, Japan. The cave was discovered on August 15, 1969, northeast of the city of Tamura and was originally named Kamayama Shonyu-do (釜山鍾乳洞). It was designated a natural heritage of the town on February 7, 1971, and renamed Abukuma-dō on June 1,1973. Visitors can traverse a 600-metre-long path inside the cave as well as a 120-metre-long exploration course to view the stalactites and stalagmites. Each stalactite has taken more than eighty million years to form. Beyond the public areas lie about 2,500 metres of cave that are not open to the public. Nearby Abukuma Cave is the smaller Irimizu Shonyu-do (入水鍾乳洞 - Irimizu Limestone Cave), discovered in 1927. Irimizu Limestone Cave was designated a National Natural Treasure on December 28, 1934. The temperature inside Abukuma-dō is approximately 15 °C and the humidity is above 90%.

== History == Abukuma-dō was discovered in September 1969 from the present Busan quarry site in an area called Abukuma Highlands (阿武隈高地), or Harachitai highlands (原地帯), in the middle of a geologic plateau formation of irregular limestone deposits, on the western slope of Mt. Otakine. Since ancient times mining for marble and limestone has been popular in that area. Limestone was also discovered at Abukuma-dō. At the year of Abukuma-dō's discovery mining in that area was suspended, and a limestone outcrop remains to this day.