Located in Iwaizumi in eastern Iwate Prefecture, Ryusen-do Cave is one of Japan's largest limestone caverns. Featuring a string of vivid blue and emerald green underground lakes, it's a must-see for those traveling in Iwate.
Ryusen-do Cave is just outside the town of Iwaizumi and is accessible by bus from JR Morioka Station.
Ryusen-do Cave is in a remote part of Iwate that's not easy to access by public transportation. The best way to get there is to take the direct JR Tohoku Bus from JR Morioka Station. Buses typically take about two hours and 15 minutes, and are covered by the Japan Rail Pass. If you are visiting Ryusen-do as a day trip, the last buses leave early, so be sure to confirm the schedule.
The cave's 120-meter deep underground lake is Japan's deepest
Only about 3,000 of the cave's estimated 5,000-meter length has been explored
Inside Ryusen-do there are four fresh water lakes, and three of them are open to the public for viewing. The deepest of these is 98 meters. The lakes are illuminated, making the water appear a vivid and ethereal blue, allowing you to see all the way to the bottom. Gazing into the abyss of the deepest is like peering into another world.
The stalactites and stalagmites that have formed throughout the cave over the eons add to its mystique, and you'll encounter extraordinary formations around every corner. One that stands out is a stalagmite that looks strikingly similar to Jizo, the Buddhist protector of children and travelers. These rock formations are very fragile, so touching them is strictly prohibited.
A number of species of bat inhabit Ryusen-do, some of which are very rare. Usually the bats are inactive during the day, but they occasionally make an appearance early in the morning or late in the afternoon. It's quite a surprise when a bat zips overhead but it makes a memorable story to tell about your trip.
As you enter Ryusen-do, you can hear fresh spring water rushing out of the cave. Much of this is bottled and sold. Ryusendo's pristine and delicious water is filled with minerals, making it especially healthy. The lucky local population gets to drink it for free from the tap. If you'd like to take a draught of Ryusen-do to go, its bottled spring water is a popular souvenir.
Far underground, Ryusen-do provides a naturally air-conditioned adventure during the sweltering Japanese summer. In fact, the temperature of the cave doesn't vary much year-round, making it quite comfortable in the winter as well.
After returning to the surface, you can walk across the street to Ryusen-shindo, a less expansive cave which houses a small science museum with displays on cavern geology and information on the area. It typically takes between one and two hours to see both caves.
After you've finished your underground exploration, you can head up to the spectacular Kitayamazaki Coast, or down to Miyako's stunning Jodogahama Beach.
You can also stay in Iwaizumi and climb Mount Ureira. This takes about half a day. The climb is easy and suitable for those of average fitness and the views are amazing.