Explore the mysteries of Ryusendo Cave, one of Japan’s three great limestone caves! Delve deep underground in Iwate Prefecture, admire the world-class transparency of the Dragon Blue lake and fantastical stalactites, including transportation and admission tips.
Introduction
Hidden deep within the mountains of Iwate Prefecture in northeastern Japan lies a mysterious underground wonderland – Ryusendo Cave. This is not only one of the “Three Great Limestone Caves of Japan,” alongside Akiyoshido Cave in Yamaguchi Prefecture and Ryugado Cave in Kochi Prefecture, but it is also world-renowned for its deep, clear, underground lakes that shimmer with a unique “Dragon Blue” light. Stepping into the cave is like entering another dimension. The spectacle of stalactites and stalagmites, the sound of flowing water, and the breathtakingly vibrant blue lake water together tell the story of Earth over millions of years. This article will take you on a journey into the mysterious world of Ryusendo Cave, from its historical significance and astonishing underground lake spectacle, to the highlights of exploring within the cave, practical visiting information, and nearby attractions, allowing you to fully plan a fantastical journey deep into the earth.
One of Japan’s Three Great Limestone Caves: History and Significance of Ryusendo Cave
Ryusendo Cave is not only famous for its beautiful underground lakes, but its geological and ecological value is also highly regarded.
Nature’s Sculpture Over Millions of Years
Ryusendo Cave is a typical limestone cave, formed by rain and groundwater eroding the limestone layers over tens of millions of years. The total length of the cave is estimated to be over 5 kilometers, with the currently confirmed portion being about 4088 meters. Approximately 700 meters of this area is open to the public as a tourist route. The remaining vast areas are still under continuous investigation, filled with unknown mystery.
Double Designation as a National Natural Monument
The precious value of Ryusendo Cave has long been recognized by the Japanese government. As early as 1938, Ryusendo Cave was designated as a National “Historic Site, Scenic Spot, and Natural Monument” of Japan under the name “Iwaizumi Yukawa and Bats“. This designation not only recognizes the geological landscape value of the cave itself but also specifically protects the five species of precious bats that inhabit the cave.
Dive into the Earth: The Astonishing Underground Lake Spectacle of Ryusendo Cave
What is most captivating about Ryusendo Cave is its several deep and clear underground lakes.
World-Class Transparency and the Secret of “Dragon Blue”
- Astonishing Transparency: The underground lakes of Ryusendo Cave boast world-class transparency. The lake water is extremely clear, with visibility extending dozens of meters, as if you can see through to the bottom at a glance.
- Mysterious “Dragon Blue”: Even under artificial lighting, these underground lakes display a deep and captivating blue color. This unique blue is called “Dragon Blue.” The reason for its vibrant blue color, in addition to the extreme purity of the water (water itself absorbs red light and scatters blue and green light), is also likely related to the reflection of sediment at the bottom of the lake and the special light environment within the cave.
- Best Time to Visit: Winter: It is said that the best time to view the underground lakes in their clearest state is winter. This is because in winter, the surface freezes and dripping from the cave ceiling decreases, making the water surface calmer with fewer ripples. Rainfall is also less, and underground water flow is stable, so sediment at the bottom of the lake is less likely to be stirred up, resulting in the highest transparency.
Explore the Three Open Underground Lakes
Currently, at least eight underground lakes have been discovered within Ryusendo Cave, three of which are open to tourists.
- First Underground Lake: Approximately 35 meters deep, it is the first blue surprise that catches your eye.
- Second Underground Lake: Approximately 38 meters deep, it also displays a captivating Dragon Blue.
- Third Underground Lake: Located at the deepest part of the tourist route, it reaches a depth of 98 meters! It is the deepest of the underground lakes currently open to the public, and looking down feels like glimpsing into the abyss of the earth. Its deep blue color is even more breathtaking.
- Unopened Fourth Underground Lake: According to surveys, there is a fourth underground lake even deeper, reaching 120 meters, making it the deepest underground lake in Japan. However, it is not currently open to the public.
Mysterious Exploration within the Cave: Stalactites and the Moon Palace
In addition to the underground lakes, the stalactite formations and unique terrain within Ryusendo Cave are also full of highlights.
Walking the Visiting Route and Highlights
- Length and Time of Visiting Route: The tourist route open to the public is about 700 meters long, and it takes about 30-40 minutes to complete the visit.
- Ascending and Descending Stairs: The route includes many stairs, especially the section leading to the Third Underground Lake observation deck, which requires climbing many steps (some sections have over 200 steps), so visiting requires a certain level of physical fitness.
- Spring of Longevity: There is a spring within the cave called the “Spring of Longevity,” and it is said that drinking its water can prolong one’s life.
- Various Stalactites: Along the way, you can see various forms of stalactites, stalagmites, columns, and flowstones (travertine terraces), all of which are natural works of art formed by groundwater dissolving limestone and depositing minerals over long periods.
Fantastic Light and Shadow “Moon Palace (Gekkyuden)”
This is a spacious area within the cave where stalactites are particularly well-developed. Illuminated by carefully designed colorful LED lights, it presents a fantastical and mysterious atmosphere like the surface of the moon, hence the name “Moon Palace.” This is also a popular spot to look for “heart-shaped” stalactites; it is said that finding one brings good luck, making it popular among couples.
Native Inhabitants of the Cave: Resident Bats
Ryusendo Cave is an important habitat for five species of bats (such as the Japanese Long-eared Bat and the Large Horseshoe Bat), and they are designated as a National Natural Monument along with the cave itself. Bats are nocturnal animals and usually hide during the day, making them difficult to see. However, in winter, you may have the chance to see bats hibernating along the visiting route. Please do not disturb them.
A World of Constant Temperature Year-Round
The temperature inside Ryusendo Cave is very stable, maintained at around 10 degrees Celsius throughout the year. Even in the hot summer, it feels quite cool inside the cave, and in winter, it feels relatively warm. This constant temperature environment is also one of the reasons why bats choose to inhabit this cave.
Visiting Information and Nearby Recommendations
Transportation
- Bus (Main Method): From the bus stop number 1 at the east exit of JR “Morioka Station,” take the JR Bus Tohoku “Hayasaka Kogen Line” and get off at the final stop “Ryusendo-mae“. The journey takes about 2 hours and 10 minutes to 2 hours and 20 minutes. Bus services are not very frequent, so it is advisable to check the latest timetable of JR Bus Tohoku in advance.
- By Car: From the Tohoku Expressway “Morioka IC,” take National Route 455 to the cave. The journey takes about 1 hour and 40 minutes to 2 hours. Ryusendo Cave has a free parking lot.
- Sanriku Railway Transfer: You can also take the Sanriku Railway to “Iwaizumi-Omoto Station” and then transfer to the Iwaizumi Town Bus (even fewer services) to Ryusendo Cave.
Admission Fees and Opening Hours
- Admission Fee: 1,100 Japanese Yen for adults (high school students and above), 550 Japanese Yen for elementary and junior high school students. (Includes admission to both Ryusendo Cave and Ryusen Shindo Science Museum). Prices may change, please refer to the official website.
- Opening Hours: Usually 8:30 AM to 5:00 PM (last entry time). During summer (May to September), it may be extended to 6:00 PM. Open year-round (but may be temporarily closed due to rising water levels inside the cave caused by heavy rain). It is recommended to check the latest information on the official website before visiting.
Suggested Clothing and Items to Bring
- Warm Clothing: The temperature inside the cave is around 10°C throughout the year, so be sure to bring a jacket or long-sleeved clothing to keep warm, even in summer.
- Non-Slip, Easy-to-Walk Shoes: The ground inside the cave can be wet and slippery, and there are many stairs, so please wear comfortable, non-slip shoes.
- Rain Gear (Depending on Conditions): During the rainy season or after rain, there may be dripping from the cave ceiling, so consider bringing light rain gear or wearing a waterproof jacket.
Ryusen Shindo Science Museum
Located across from Ryusendo Cave, it is the world’s first science museum established inside a natural cave. It exhibits the formation process of the cave, types of stalactites and stalagmites, and archaeological materials such as ancient pottery, stone tools, and animal bones discovered here. The admission ticket for Ryusendo Cave includes admission to this museum, so you can visit both together.
Conclusion
Ryusendo Cave, this underground palace hidden deep in the mountains of Iwate Prefecture, has become a dazzling natural gem in the Tohoku region of Japan with its world-class transparent “Dragon Blue” underground lakes, fantastical stalactite formations, and rich ecological and geological value. Diving into this cool world with a constant temperature year-round, exploring the natural wonders sculpted by the Earth over millions of years, and feeling the mystery and tranquility brought by the deep blue lake water will undoubtedly be an unforgettable experience. Although transportation requires some time, the unique underground spectacle presented by Ryusendo Cave is definitely worth the special trip to see for yourself. Prepare your jacket and curiosity, and embark on a blue adventure deep into the earth!
Which part of Ryusendo Cave are you most interested in? The mysterious “Dragon Blue” underground lakes, or the fantastical “Moon Palace”? If you found this guide helpful for exploring the hidden gems of Iwate, please share it with friends who also love nature!
