Deep beneath the earth in Iwatizumi Town, Iwate Prefecture, lies a mysterious underground world—Ryusendo Cave. Counted among Japan’s Three Great Limestone Caves, this cavern captivates visitors with its underground lakes boasting world-class transparency and stalactites formed over hundreds of millions of years, creating a fantastical subterranean realm.
True to its name meaning “Dragon Spring Cave,” crystal-clear cobalt blue underground lakes stretch through the cave’s depths, reaching a maximum depth of 98 meters. The water temperature remains constant at approximately 10°C (50°F) year-round, creating an otherworldly space where time seems to stand still. Long revered by locals as a “mystical spring,” this sacred site continues to draw visitors seeking purification of body and mind and renewed vitality.
The Allure of This Sacred Site
The discovery of Ryusendo Cave dates back approximately 1,200 years to the Heian period. Legend tells of a local hunter who stumbled upon this cave while pursuing game, and since then, it has been carefully protected by the local community as a “sacred place where dragons dwell.”
Formal academic surveys began in the 1920s. Subsequent explorations revealed new underground lakes and stalactites, leading to the cave’s designation as a National Natural Monument in 1938. The currently confirmed total length of the cave extends approximately 4,088 meters, though it’s believed to continue much deeper—its full extent remains unexplored.
The name “Ryusendo” derives from the legend of a dragon deity dwelling within the cave. According to local lore, during a severe drought, villagers performed rain-invoking rituals in this cave, and blessed rains immediately began to fall. This tale is still passed down through generations today.
Ryusendo’s greatest attraction is undoubtedly its three underground lakes. The first lake reaches a depth of 35 meters, the second 38 meters, and the third an astounding 98 meters. The water transparency measures 41.5 meters—among the highest in the world—so clear that the lake bottom is visible, creating the mesmerizing blue known as “Dragon Blue.”
The cave maintains a constant temperature of approximately 10-11°C (50-52°F) year-round, feeling refreshingly cool in summer and surprisingly warm in winter. The stalactites hanging from the ceiling, stalagmites rising from the floor, and curtain-like limestone formations are said to grow just one centimeter every 100 years—natural artworks created over hundreds of millions of years.
The area called “Gekkyuden” (Moon Palace) is particularly remarkable, where pure white stalactites spread across the ceiling like moonlight illuminating the space, capturing the hearts of countless visitors.
What sets Ryusendo apart from other limestone caves is the overwhelming presence of its underground lakes. With unparalleled transparency and depth, these lakes leave viewers speechless with their beauty. The cobalt blue water surface illuminated by lighting appears like a gateway to another world.
The cave also houses the “Ryusen New Cave Science Museum,” where visitors can learn about how limestone caves form and the creatures that inhabit them. Exhibits featuring rare cave-dwelling creatures found only here, such as cave freshwater clams, are among the highlights.
Following recovery from typhoon damage in 2016, new lighting equipment was installed, enabling even more fantastical atmospheric presentations.
Spiritual Benefits and Effects
Ryusendo has long been recognized as a “power spot for purification and renewal.” The underground lakes believed to be home to a dragon deity are said to offer these blessings:
Mind-Body Purification & Healing: The pure air within the cave and the mystical presence of the underground lakes are said to wash away daily stress and fatigue.
Wealth & Financial Fortune: The dragon deity has been regarded since ancient times as a guardian of treasures, drawing many visitors who pray for improved financial fortune.
Good Luck & Evil Warding: The clear water welling up from deep underground is believed to have the power to dispel negative energy, making this a popular destination before embarking on new beginnings.
Good Relationships & Matchmaking: According to legend, visitors may form pure connections as clear as the water itself, making couple visits popular.
What many visitors sense at Ryusendo is an energy of “deep silence and purification.” Completely isolated from the surface world within the cave, visitors can enjoy precious time to face themselves, free from everyday noise.
Standing before the third underground lake, many experience what they describe as “a sensation of having their hearts cleansed” by its overwhelming depth and transparency. This place is filled with a primal, powerful energy—as if one can feel the very heartbeat of the Earth.
“The moment I saw the third underground lake, tears began flowing. I don’t know why, but I felt I had touched something precious.” (Woman in her 40s, Tokyo)
“I visited during a time when I was hesitating about changing jobs. After leaving the cave, my mind was strangely made up. I think the silence allowed me to recognize my true feelings.” (Man in his 30s, Miyagi Prefecture)
Best Times to Visit
A season of beautiful fresh greenery. The surrounding mountains begin to bud, allowing visits in refreshing air. The Golden Week period is crowded, so mid to late April weekdays are recommended. Since the cave maintains a constant temperature year-round, this is also a great time to enjoy the temperature difference with the outside air. The most popular season. Even on midsummer days exceeding 30°C (86°F) outside, the cave remains at about 10°C (50°F)—natural air conditioning. It bustles with tourists seeking cool relief, with the Obon period in August being particularly crowded. Weekday mornings in July are the best timing. During autumn foliage season, the surrounding mountains are dyed in reds and yellows, allowing visitors to enjoy both cave exploration and leaf viewing. Peak foliage runs from mid-October to early November. Less crowded than summer, this is a hidden gem period for leisurely viewing. The fewest tourists, allowing quiet enjoyment of the cave. While temperatures outside are below freezing, the cave feels warm at about 10°C (50°F). However, be cautious of icy roads. Winter tires are essential. Right After Opening (8:30–9:30 AM): The emptiest time slot. Before tour groups arrive, you can have the mystical space to yourself in complete silence. Morning (10:00 AM–12:00 PM): Group tours begin increasing, but there’s still relative space. Afternoon (1:00–4:00 PM): The busiest period. Lines may form especially on weekends and holidays. Near Closing (4:00–5:00 PM): Crowds decrease again, allowing calm viewing. Gazing at the underground lakes in the evening quiet is exceptional.
Recommendation: ★★★★☆
Recommendation: ★★★★★
Recommendation: ★★★★★
Recommendation: ★★★☆☆
Visitor’s Guide
Ryusendo is both a sacred site and a precious Natural Monument. Please observe these guidelines:
1. Don’t Touch the Stalactites: The oils and warmth from hands can stop stalactite growth. View only from outside the barriers.
2. View Quietly: Sound echoes easily in the cave, and loud voices disturb other visitors. Maintain quiet behavior appropriate for a sacred space.
3. Take Your Trash: To preserve the cave’s pristine environment, always take your trash with you.
4. Limit Flash Photography: It may affect the cave ecosystem.
Entrance → Hyakken Corridor (approx. 5 min): Just after entering the cave, this passage of about 100 meters gradually draws you into the underground world.
Chomei-no-Fuchi / Pool of Longevity (approx. 3 min): A clear stream flowing through the cave. Legend says drinking this water brings longevity.
Gekkyuden / Moon Palace (approx. 5 min): Pure white stalactite formations spreading across the ceiling. One of the most beautiful photo spots.
First Underground Lake (approx. 5 min): 35 meters deep. The first underground lake you encounter—its transparency is stunning.
Second Underground Lake (approx. 5 min): 38 meters deep. The cobalt blue illuminated by lighting is fantastical.
Third Underground Lake (approx. 10 min): 98 meters deep. Ryusendo’s greatest highlight. A place to linger and contemplate.
Standard Viewing Time: Approximately 40 minutes to 1 hour; 1 hour 30 minutes for thorough viewing
- Clothing: The cave is about 10°C (50°F), making long sleeves essential even in summer. Wear comfortable walking shoes (sneakers recommended).
- What to Bring: Camera, handkerchief (humidity is high), small backpack
- What to Avoid: High heels, sandals, miniskirts (many stairs)
Basic Information
Address: 1-1 Kaminari, Iwaizumi, Iwaizumi-cho, Shimohei-gun, Iwate Prefecture
By Car:
- Approximately 2 hours from Morioka IC via National Route 455
- Approximately 1 hour from Miyako City via National Route 455
- Parking: Approximately 500 spaces (free)
By Public Transportation:
- JR Bus “Iwaizumi” line from JR Morioka Station, approximately 2 hours 10 minutes, get off at “Ryusendo-mae”
- Approximately 25 minutes by taxi from Sanriku Railway Iwaizumi-Omoto Station
Visiting Information
- Hours: 8:30 AM–5:00 PM (until 6:00 PM May–September)
- Closed: Open year-round
- Admission: Adults ¥1,100, Elementary/Junior High ¥550 (includes Ryusen New Cave Science Museum)
- Duration: Approximately 40 minutes to 1.5 hours
- Official Website: https://www.iwate-ryusendo.jp/
- Contact: 0194-22-2566
Area Information
Ryusen New Cave Science Museum (3-min walk)
Located right next to Ryusendo Cave. Learn about cave formation and the rare creatures that inhabit them. Included in the admission ticket, so definitely worth a visit.
Akkado Cave (30 min by car)
Japan’s longest limestone cave (total length approximately 23 km). Popular for its wild exploration-style courses. Offers a different charm from Ryusendo.
Jodogahama Beach (approx. 1 hour by car)
A scenic spot representing the Sanriku Coast. The contrast of white rocks and blue sea is beautiful, and many tourists visit it together with Ryusendo.
Rest House Ryusendo
- In Ryusendo parking area
- Specialties: Ryusendo Black Pork Curry (¥1,100), Iwaizumi Yogurt Soft Serve (¥400)
- Hours: 9:00 AM–5:00 PM
Michi-no-Eki Iwaizumi (5 min by car)
- Specialties: Tankaku Beef Steak Bowl (¥1,800), Ryusendo Water Coffee (¥350)
- Full selection of Iwaizumi town specialty products
- Hours: 9:00 AM–6:00 PM
Minshuku Kawamura (10 min by car)
- Known for local wild vegetable cuisine
- Specialty: Wild Vegetable Soba Set (¥1,200)
- Hours: 11:00 AM–2:00 PM, 5:00 PM–8:00 PM
Souvenirs & Local Products
- Ryusendo Water: Mineral water from the cave spring. Known for its smooth taste (500ml ¥150)
- Iwaizumi Yogurt: Nationally famous rich yogurt (sweetened and unsweetened varieties)
- Ryusendo Coffee: Drip coffee brewed with Ryusendo water
- Tankaku Beef Products: Processed products using rare Iwaizumi-raised Tankaku beef
Model Itineraries
Half-Day Course (approx. 4 hours)
9:00 AM Arrive at Ryusendo, tour (1.5 hours)
10:30 AM Ryusen New Cave Science Museum (30 min)
11:00 AM Lunch at rest house (45 min)
11:45 AM Souvenir shopping at Michi-no-Eki Iwaizumi (30 min)
12:15 PM Depart
Full-Day Course (approx. 8 hours)
9:00 AM Arrive at Ryusendo, tour (1.5 hours)
10:30 AM Ryusen New Cave Science Museum (30 min)
11:00 AM Lunch
12:00 PM Travel to Akkado Cave, tour (2 hours)
2:00 PM Travel to Jodogahama Beach (1 hour)
3:00 PM Explore Jodogahama (1.5 hours)
4:30 PM Return journey
Visitor Reviews and Experiences
“A Life-Changing Experience” (Man in his 50s, Saitama Prefecture)
“Standing before the third underground lake, I felt an indescribable emotion. Transparent water 98 meters deep. Feeling the weight of hundreds of millions of years, I realized how small my worries were.”
“Perfect Summer Refresh” (Woman in her 30s, Sendai City)
“I visited on a scorching August day. The moment I entered the cave, I was enveloped in cool air and felt revived. Gazing at the mystical underground lakes, I experienced a strange sensation of my heart cooling down too.”
“Enjoyable with Children” (Woman in her 40s, Iwate Prefecture)
“Visited with my 3rd-grade son. There are many stairs, but children can tour without problems. My son was thrilled by the blue of the underground lakes. He also enjoyed the science museum exhibits.”
Frequently Asked Questions
Q: Can I visit in a wheelchair or with a stroller?
A: The cave has many stairs, making wheelchair or stroller access difficult. Baby carriers are possible, but be cautious as some areas are slippery.
Q: Can I bring pets?
A: Pets are not allowed in the cave. There are no pet-sitting facilities in the parking lot.
Q: Can I eat or drink inside the cave?
A: Eating and drinking inside the cave is prohibited. Please use the rest house before or after your visit.
Q: Is it okay for people with claustrophobia?
A: The viewing paths are relatively wide with good ceiling height, so most people can tour without problems. However, there are some narrow sections, so please consult with staff beforehand if concerned.
Summary
Ryusendo is a mystical underground world carved by hundreds of millions of years of time. The underground lakes boasting world-class transparency and the natural beauty of stalactite formations leave deep impressions on all who visit.
True to its name “Dragon Spring Cave,” this place is filled with an inexplicable, mysterious power. Time spent in this mystical space, far from daily life and deep within the earth, purifies body and mind while imparting new vitality.
Though approximately 2 hours by car from Morioka, it’s well worth the journey. Combined with Sanriku Coast sightseeing, you can fully experience the natural wonders of Iwate.
The blue of the underground lakes, the white of the stalactites, and the ancient, unchanging silence—may your time at Ryusendo leave a deep impression on your heart.
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*Information in this article is current as of December 2025. Please verify the latest details via the official website before visiting.*
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