The best limestone caves in Japan are considered to be Ryugado in Kochi Prefecture, Akiyoshido in Yamaguchi Prefecture, and Ryusendo in Iwate Prefecture. Ryusendo is a limestone cave that has been designated as a natural treasure of Japan, with a confirmed length of 3,631 meters as of 2012. Abundant clear water wells up from the bottom of the cave, creating rivers and deep lakes underground, the third of which has a depth of 98 meters, and the fourth lake (not open to the public) is even deeper at 120 meters. A survey of the cave system has revealed many other caves branching off, such as turtle rock cavern, and a cavern that plays habitat to several species of bats. In fact, five bat varieties inhabit the cave, which is a rare phenomenon.

On the day that we visited, it was rainy and awfully humid. At the entrance of Ryusendo, there was fog as far as the eye could see.

The rainfall inside the cave transformed it into a romantic tunnel.

The second underground lake, with a depth of 38 meters. Light shimmering off the lake's surface makes it sparkle like an emerald, giving it a mysterious beauty.

It's so clear that you can see the bottom.

A stone naturally shaped like the bodhisattva Jizo can also be found within Ryusendo. How mysterious!

The temperature outside on that day was around 34°C yet inside the cave it was 10.8°C How mysterious! For a survey of the cave, I advise anyone planning to visit here to wear plenty of layers!

The cave is narrow and winding, and it's uneven under foot, so walkways have been constructed that follow the natural shape of the cave. The walkways are narrow and slippery, so be careful!

A variety of artwork shaped by nature's hand can be seen within Ryusendo.

Ryusendo
Location: 1-1 Kannari, Iwaizumi, Iwaizumi-cho, Shimohei-gun, Iwate
Opening hours: 8:30 a.m. to 5 p.m. (From May to September: 8:30 a.m to 6 p.m.)
Getting there: Take the JR Tohoku bus "Morioka - Iwaizumi (Ryusendo)" that can be boarded from bus stop No. 1 outside the east exit of JR Morioka Station. The journey takes approximately two hours.