Complete Guide to Ryusenso Underground Lake Water (Iwate Prefecture): The Charm and Characteristics of the Mysterious Natural Water of One of Japan’s Three Great Stalactite Caves
Ryusenso, located in Iwate Town, Shimohei District, Iwate Prefecture, is known as one of Japan’s three great stalactite caves, and the “Ryusenso Underground Lake Water” that springs from its underground lake is a natural water that has garnered national attention for its high transparency and abundant minerals. This article provides a detailed explanation from every angle, from the characteristics of this mysterious water to its health effects and methods of purchase.
Ryusenso: The Mystery of One of Japan’s Three Great Stalactite Caves
History and Overview of Ryusenso
Ryusenso is a stalactite cave designated as a natural monument by the Japanese government, located in Iwate Town, Iwate Prefecture. It is counted among Japan’s three great stalactite caves alongside Akiyoshi Cave in Yamaguchi Prefecture and Ryuga Cave in Kochi Prefecture. The known total length of passages in the cave is over approximately 4,000 meters, of which approximately 700 meters are open to the public.
There are multiple underground lakes within the cave, and eight have been confirmed so far. Three of these are open to the public, and in particular, the Third Underground Lake boasts an astounding depth of 98 meters. These underground lakes, possessing some of the highest transparency in the world, have become the greatest attraction of Ryusenso.
The Mechanism Behind the Creation of Underground Lake Water
The water of Ryusenso’s underground lake is naturally filtered as rain and snow that fall on surrounding mountains pass through limestone layers over many years, eventually reaching deep underground. During this process, impurities are removed while mineral components such as calcium contained in limestone dissolve into the water in appropriate amounts.
The natural filtration system created by limestone layers is realized through a complex layered structure of multiple geological strata. This natural filtering process is what produces the incomparable transparency and purity of Ryusenso’s water.
Characteristics of Ryusenso Underground Lake Water
World-Class Transparency
The most distinctive feature of Ryusenso’s underground lake is its overwhelming transparency. The lake’s transparency is considered among the highest in the world, boasting a clarity so pristine that the bottom can be seen tens of meters deep. This transparency is achieved through long-term filtration via limestone layers and an environment deep underground with almost no external contamination.
Visitors to Ryusenso are fascinated by the mysterious blue radiance of the underground lake called “Dragon Blue.” This blue is a natural phenomenon created by the high purity of the water and the refraction of light—a beauty that can never be artificially replicated.
Mineral Composition and Water Quality Characteristics
Ryusenso underground lake water is natural water containing appropriate amounts of calcium and magnesium. With a hardness of approximately 50mg/L, it is soft water that suits Japanese palates very well, making it easy to drink.
Principal mineral components:
- Calcium: Essential for maintaining healthy bones and teeth
- Magnesium: Involved in enzymatic reactions within the body
- Sodium: Regulates body fluid balance
- Potassium: Supports blood pressure regulation and muscle function
The pH value is weakly alkaline (approximately pH 7.5-8.0), making it suitable for neutralizing the acidic tendency of modern people’s body constitution.
Water Temperature and Freshness
Ryusenso’s underground lake maintains a constant temperature of approximately 10 degrees Celsius throughout the year. This stable low-temperature environment is an important factor in preserving the freshness and quality of the water. Water that emerges above ground is also cold and refreshing, and is particularly enjoyed by many people as a natural cold drink during summer months.
Health Effects of Ryusenso Underground Lake Water
Gentleness to the Body: Benefits of Ultra-Soft Water
Ryusenso water, with a hardness of approximately 50mg/L, is ultra-soft water that is easily absorbed by the body and does not place a burden on the stomach and intestines. It is also suitable for preparing baby formula, and can be safely consumed by everyone from small children to the elderly.
Soft water pairs excellently with Japanese cuisine; when used to cook rice, it produces fluffy, well-cooked grain, and when brewing tea or coffee, it brings out the original flavor of the ingredients to their fullest. When making broth, it efficiently extracts umami components from kombu and bonito flakes.
Mineral Supplementation and Bodily Balance
Modern diets often lack minerals, which can be naturally replenished from Ryusenso water. The balance between calcium and magnesium is particularly good, supporting bone health maintenance and normal muscle function.
Magnesium is involved in approximately 300 types of enzymatic reactions and plays important roles in energy metabolism and nerve transmission. Daily consumption of Ryusenso water allows you to obtain these minerals effortlessly.
Detoxification Effects and Metabolism Enhancement
Consuming appropriate amounts of highly pure natural water promotes the elimination of bodily waste. Because Ryusenso water has extremely few impurities, it smooths water metabolism within the body and supports detoxification at the cellular level.
Its weakly alkaline nature also helps neutralize the acidic tendency of modern people’s body constitution and aids in balancing the body’s acid-base equilibrium. This is thought to contribute to fatigue recovery and immune function maintenance.
The Taste and Drinking Methods of Ryusenso Underground Lake Water
Taste Characteristics
Ryusenso underground lake water is characterized by a mellow flavor with a soft mouthfeel and a clean aftertaste. With the lack of distinctive flavor typical of ultra-soft water, when chilled, its refreshing quality becomes even more pronounced.
While some mineral waters have distinctive flavors, Ryusenso water is extremely pure, allowing you to appreciate the natural deliciousness of water itself. Many people comment, “I didn’t know water could taste this good.”
Recommended Drinking Methods
Drinking plain
The simplest method that allows you to enjoy the water’s natural flavor. Chilling it to 5-10 degrees Celsius in a refrigerator increases its refreshing quality and enhances its deliciousness.
In tea and coffee
Soft water is ideal for bringing out the flavor of tea leaves and coffee beans. When brewing Japanese tea, especially green tea or gyokuro, using Ryusenso water allows umami components to extract well, resulting in a mellow taste.
In cooking
It can be used in all kinds of cooking—rice cooking, simmered dishes, soups, and more. It particularly pairs well with Japanese cuisine and is suited to delicate cooking that brings out the essence of ingredients.
In whiskey highballs and shochu mizuwari
When used for shochu mizuwari or whiskey highballs, it mellows the sharp edge of alcohol, resulting in a smoother flavor.
Product Lineup of Ryusenso Underground Lake Water
Bottled Products
Ryusenso underground lake water is primarily sold in the following sizes:
- 500ml bottles: Convenient for carrying, ideal for hydration on the go or at the workplace
- 2L bottles: Popular for home use, offering excellent value for money
- 350ml cans: Sold in some vending machines
Bottles are lightweight and easy to handle, with a shelf life of approximately 2 years from manufacture, allowing for long-term storage.
Gift Sets
Gift boxes containing multiple bottles are also sold for gifting purposes. As a specialty product of Iwate Prefecture, they are frequently chosen for midyear gifts, year-end gifts, and thank-you gifts, and are well-received by recipients.
Beautifully packaged boxed sets are ideal gifts for special people.
Methods of Purchasing Ryusenso Underground Lake Water
Purchase at the Site
Ryusenso Sightseeing Center
When visiting Ryusenso, you can purchase water at the attached sightseeing center and gift shops. Drinking water as a memento of your visit, especially after seeing the underground lake in person, offers an exceptional taste.
Limited-edition packaging and commemorative bottles not available through online retailers are sometimes sold at the site.
Online Purchase
Official Online Shop
You can purchase directly from the official websites of Iwate Town or Ryusenso. Using a regular purchase plan allows you to continue purchasing at favorable prices.
Major E-commerce Sites
The water is also available on major e-commerce platforms such as Amazon, Rakuten Ichiba, and Yahoo! Shopping. You can save money by taking advantage of point rewards and sales periods.
Buying in bulk often provides free shipping, and having heavy water delivered to your home is a major advantage.
Purchase at Physical Stores
Supermarkets and Souvenir Shops in Iwate Prefecture
The water is relatively easy to find at major supermarkets, roadside stations, and souvenir shops throughout Iwate Prefecture.
Antenna Shops in the Tokyo Metropolitan Area
You can purchase it at Iwate’s antenna shop in Tokyo’s Ginza district, “Iwate Ginza Plaza,” and similar establishments. Even if you cannot visit Iwate, you can obtain it in the Tokyo metropolitan area.
Department Stores
Some department stores’ food sections carry it. It is certain to be available during Iwate Prefecture product fairs and similar events.
Ryusenso Sightseeing and Water Experience
Points to Note When Visiting Ryusenso
Visiting Ryusenso itself, the source of Ryusenso underground lake water, is the best way to understand this water more deeply and enjoy it more fully.
Highlights
- First Underground Lake: 35 meters deep, with beautiful emerald green coloring
- Second Underground Lake: 38 meters deep, with a mystical atmosphere
- Third Underground Lake: 98 meters deep, Japan’s deepest publicly accessible underground lake
- Underground Lake Water Tasting Point: You can sample water freshly springing from the source
The cave interior maintains approximately 10 degrees Celsius year-round, so bringing a jacket even in summer is recommended. Since some areas are slippery, wear easy-to-walk-in shoes.
Access Information
Location
〒027-0501 Iwate-cho, Shimohei District, Iwate Prefecture, Iwate, Kaminarishiro 1-1
Transportation
- By car: Approximately 2 hours from Morioka City, via Route 455 from the Morioka South IC on the Tohoku Expressway
- Public transportation: Approximately 2 hours by bus from JR Morioka Station (advance confirmation of schedules is recommended as service is limited)
Hours of Operation
- May-September: 8:30 AM-6:00 PM
- October-April: 8:30 AM-5:00 PM
- Open year-round (temporary closures may occur due to weather conditions)
Admission Fees
- Adults: ¥1,100
- Elementary and middle school students: ¥550
Nearby Attractions
When visiting Ryusenso, you can also enjoy nearby tourist spots.
Ryusenso Youth Travel Village
Features a camping ground and bungalows where you can spend time leisurely in nature.
Anya Cave
Japan’s longest stalactite cave with a total length exceeding 23,700 meters. Adventure courses are available for genuine cave exploration experiences.
Iwate Town Townscape
Iwate Town retains its historic character, where you can enjoy dishes made with local ingredients and local specialties.
Ryusenso Underground Lake Water and Environmental Conservation
Sustainable Water Extraction
Water extraction from Ryusenso’s underground lake is carefully managed to minimize environmental impact. The water level and water quality of the underground lake are regularly monitored to ensure extraction occurs within limits that do not disrupt natural balance.
Iwate Town is committed to passing this precious natural resource on to future generations through efforts in forest conservation around the area and water source preservation.
Contribution to Regional Revitalization
The sale of Ryusenso underground lake water has become one of Iwate Prefecture’s important industries and makes a significant contribution to regional economic activation. Combined with tourism, it enhances the appeal of the entire region.
Purchasing the product indirectly supports regional nature conservation activities and regional revitalization.
Comparison with Other Natural Waters
Differences from Other Famous Japanese Waters
Japan has many famous waters, but Ryusenso underground lake water has distinctive characteristics in the following respects:
High Transparency
The transparency of the underground lake is world-class, standing out when compared to many other famous waters.
Unique Water Source Environment
The fact that water is extracted from a lake deep underground distinguishes it from other spring water and mountain water sources.
Hardness Balance
Hardness of approximately 50mg/L is exceptionally easy to drink among soft waters and has a perfect balance for cooking.
Comparison with Famous Waters Worldwide
Compared to European hard water, Ryusenso water is overwhelmingly soft and suits Japanese palates. Though mineral content is modest, this actually makes it easier to drink daily.
Storage Methods and Expiration Dates of Ryusenso Underground Lake Water
Proper Storage Methods
Unopened bottles
Can be stored at room temperature away from direct sunlight. Storage in a cool, dark place avoiding high heat and humidity is ideal.
After opening
Store in the refrigerator and consume as soon as possible (within 2-3 days). If the bottle has been drunk directly from, it is recommended to consume it the same day as bacteria multiplication becomes likely.
Shelf Life
The shelf life of bottled Ryusenso underground lake water is approximately 2 years from manufacture. The expiration date is printed on the bottle label or cap.
Though water may still be drinkable after the expiration date has passed, it is recommended to drink within the period from a quality assurance perspective.
As Emergency Reserve Water
Ryusenso underground lake water, which can be stored long-term with stable quality, is also excellent for emergency reserve supplies. The recommendation is to reserve a minimum of 3 days’ supply (preferably 1 week), at a rate of approximately 3 liters per person per day.
Regularly check expiration dates and use older supplies in daily life while replenishing with new stock—a “rotating stock” method is effective.
Recipes Using Ryusenso Underground Lake Water
Basic Rice Cooking
Rice cooked with Ryusenso water becomes fluffy and its natural sweetness is enhanced.
- Use Ryusenso water when rinsing rice as well
- Soak for 30 minutes or more using standard water proportions
- Cook in a rice cooker
Because of the soft water, rice surfaces cook softly, resulting in a chewy texture.
Making Broth
Making basic broth, a foundation of Japanese cuisine, becomes far more delicious using Ryusenso water.
Kombu Broth
- Lightly wipe the surface of the kombu
- Place kombu in Ryusenso water and let sit for 30 minutes or more
- Heat slowly over low heat and remove kombu just before boiling
Soft water efficiently extracts umami components (glutamic acid) from kombu.
Brewing Green Tea
- Warm the teapot and teacup
- Cool Ryusenso water to 70-80 degrees (50-60 degrees for gyokuro)
- Place tea leaves in the teapot and pour the water
- Steep for 1-2 minutes and serve
Soft water is ideal for bringing out the delicate fragrance and umami of tea leaves.
Summary: The Appeal of Ryusenso Underground Lake Water
Ryusenso underground lake water from Iwate Town, Iwate Prefecture, is a natural water born in the special environment of one of Japan’s three great stalactite caves, boasting world-class transparency.
Main Characteristics
- Long-term natural filtration through limestone layers
- Ultra-soft water with hardness of approximately 50mg/L, easy to drink
- Balanced mineral content including calcium and magnesium
- Weakly alkaline, gentle on the body
- Maintains stable temperature of approximately 10 degrees Celsius year-round
Ways to Enjoy It
- Drink plain to savor the water’s natural deliciousness
- Use in tea, coffee, and cooking to enhance the flavor of ingredients
- Visit Ryusenso to experience the mystery of the underground lake in person
Ryusenso underground lake water is not merely a beverage but a precious resource created by Iwate Prefecture’s abundant nature and geological miracles. By drinking this water, even from far away, you can feel connected to Ryusenso’s mystical underground lake.
From daily water intake for health maintenance to special tea and cooking occasions, experience the blessings of Ryusenso underground lake water in all your activities. And if the opportunity arises, we recommend visiting Ryusenso in person to see with your own eyes the source where this wonderful water is created.
Ryusenso underground lake water—a natural treasure that Iwate Prefecture is proud to offer. In every drop, the bounty of the earth refined over thousands of years and the power of pristine nature are condensed.
