Ryusendo cavern

"Ryusendo"Dragon-Blue Underground Lake That Is Proud of Its World-Leading Transparency
  • Address:1-1 Iwaizumi Kaminari Iwaizumi-cho Shimohei-gun Iwate
  • TEL:0194-22-2566
  • URL:http://www.iwate-ryusendo.jp/
  • Recommended Season: All seasons (The transparency of the underground lake gets very clear in winter.)
  • The Degree of Secret Places:

Outline "Ryusendo" is one of Japan's three largest limestone caverns.
It was designated as one of Japan's natural treasures, along with the five kinds of bats that inhabit in the cave.
The total confirmed length of the cave is currently 3.6km (2.2miles), although the cave may extend over 5km (3.1miles).
The underground lake is formed by the ground water that is in the cave.
The cave consists of three underground lakes, the first of which as a depth of 35 meters (115ft), the second of which has a depth of 38 meters (125ft) and the third of which as a depth of 98 meters (322ft) at deepest.

Since all the underground lakes are proud of their crystal clear blue water, called 'Dragon-Blue', everybody uses it as the nickname.
Even though this is not open to the public yet, the fourth underground lake has a depth of over 120 meters (394ft) transparent to over 40 meters, a world-leading underground lake.