Current date: 2025-12-19 (JST)
The coastline of northern Kyushu is rugged and wild, a place where the land meets the often-turbulent Genkai Sea. It’s here, just a short drive from the city of Karatsu in Saga Prefecture, that you’ll find Nanatsugama—the Seven Caves. This is not a single cavern but a series of seven sea caves carved into a dramatic basalt cliff. The dark, hexagonal columns of rock, a formation known as columnar jointing, create a stark and beautiful contrast against the emerald-green water.
I had heard that the best way to see the caves was from the water, and the descriptions were accurate. From the clifftop observation deck, the view is impressive, but it’s the boat tour that takes you right up to the mouth of these caverns that provides the true sense of their scale and power. This guide is for the traveler looking to experience this natural wonder, with practical advice on how to get there, what to expect, and how to make the most of your visit.
Overview
Nanatsugama is a designated National Natural Monument of Japan. The seven caves were formed over millennia by the relentless waves of the Genkai Sea eroding the basalt cliffs. The largest of the caves has an entrance 3 meters wide and extends 110 meters deep. When the sea is calm, sightseeing boats can navigate right inside, offering a unique perspective of the geological formations.
There are two primary ways to experience Nanatsugama:
1.From the Land: A well-maintained park area sits atop the cliffs. There are walking paths, a grassy field perfect for a picnic, and an observation deck that provides a panoramic view of the caves and the surrounding coastline. You can feel the sea breeze and hear the waves crashing below.
2.From the Sea: The most popular option is the Ika-maru sightseeing cruise, which departs from nearby Yobuko Port. This 40-minute tour gives you an up-close look at the caves that you simply can’t get from the land.
Why This Place Is Worth Visiting
Nanatsugama is for travelers who are drawn to dramatic coastal landscapes and the raw power of nature. It’s a perfect destination for photographers, geology enthusiasts, and anyone looking for a scenic escape from the city. The contrast between the dark, geometric rock formations and the clear, turquoise water is visually stunning.
This is not a place for a full-day excursion on its own, but it is an excellent and memorable stop as part of a larger trip around the Karatsu and Yobuko area. It’s for those who appreciate a boat trip with a purpose and enjoy seeing a natural landmark from a unique vantage point. If you are prone to seasickness, you might prefer to stick to the clifftop park, which offers its own rewarding views.
How to Get There
Accessing Nanatsugama is most convenient by car, as public transportation is limited. The site is located about a 30-40 minute drive from central Karatsu.
By Car:
•There is a large, free parking lot at the Nanatsugama Park on the clifftop. From here, it’s a short walk to the observation deck and the start of the walking trails.
By Boat (Ika-maru Cruise):
•The sightseeing boats depart from Yobuko Port, which is about a 15-minute drive from Nanatsugama itself. You cannot board the boat at the caves.
•From Karatsu Station: Take a bus to Yobuko (about 30 minutes), then walk to the Marinepal Yobuko ticket office at the port.
It’s important to understand that the land-based park and the boat tour departure point are in two different locations. Plan your transportation accordingly.
Costs & Fees
Viewing Nanatsugama from the clifftop park is completely free, including parking. The cost is associated with the boat tour.
| Item | Cost (Adult) | Cost (Child) | Notes |
| Nanatsugama Park | Free | Free | Includes parking and access to observation deck |
| Ika-maru Boat Tour | ¥2,000 | ¥1,000 | 40-minute cruise from Yobuko Port 1 |
The boat tour is subject to cancellation due to weather or rough seas. The tour narration is in Japanese only. Prices are as of December 2025.
Best Time to Visit
The best time to visit Nanatsugama is from spring to autumn (April to November) when the weather is milder and the sea is generally calmer, increasing the chances that the boat tour will operate and be able to enter the caves.
•Time of Day: On a sunny day, the water inside the caves appears a brilliant emerald green, which is best seen when the sun is high. The afternoon light also beautifully illuminates the cliffs.
•Crowd Patterns: The area is most popular on weekends and national holidays. If you are taking the boat tour, arriving for one of the earlier departures (they start around 9:30 AM) can help you avoid the biggest crowds.
•Weather: This is a coastal attraction, and its enjoyment is highly dependent on the weather. Check the forecast before you go. Strong winds and high waves will lead to the cancellation of boat tours.
Things to Know Before You Go
•Check Boat Operations: If you plan to take the boat tour, it is crucial to check if it is operating on the day of your visit. You can call the Marinepal Yobuko office (+81 955-82-3001) or check their website, though information may be in Japanese.
•Footwear: If you are exploring the clifftop park, wear comfortable walking shoes. The paths are well-maintained but can be uneven in places.
•No Facilities at the Park: There are very few facilities at the Nanatsugama Park itself, aside from a toilet. Bring your own drinks and snacks.
•Seasickness: The Genkai Sea can be choppy. If you are prone to motion sickness, take precautions before boarding the boat tour.
Nearby Places Worth Adding
1.Yobuko Morning Market: One of Japan’s most famous morning markets, located right at Yobuko Port. It’s a fantastic place to try fresh squid (ika), the local specialty, either as sashimi or grilled.
2.Karatsu Castle: Overlooking Karatsu Bay, this beautiful castle is a reconstruction but offers fantastic views and interesting historical exhibits. It’s a great way to learn about the region’s history.
3.Hado Cape: A scenic cape with an underwater observatory tower, offering another way to experience the marine life of the Genkai Sea. It’s a short drive from Nanatsugama.
Where to Stay (Affiliate Section)
There are no accommodations directly at Nanatsugama. Most visitors stay in the nearby city of Karatsu, which serves as an excellent base for exploring the entire area. Karatsu offers a good range of hotels and traditional ryokan to suit different budgets.
Here are a couple of highly-rated options in Karatsu:
1.Mercure Saga Karatsu Resort: With an excellent 8.2/10 rating from over 500 reviews, this newly renovated resort offers great value. It’s located near Higashi-Karatsu Station and features a spa, restaurants, and comfortable rooms. It’s a solid choice for travelers looking for modern hotel comforts.
2.Riverside Hotel Karatsu Castle: Boasting an impressive 8.8/10 rating, this hotel is praised for its spacious, well-equipped rooms and convenient location. It offers great views and is a perfect base for exploring both the city and the coastline.
Staying in Karatsu allows you to enjoy the city’s restaurants and attractions in the evening after a day of coastal exploration.
→ Search for hotels in the Karatsu area on Agoda — Use this link to check availability and find more options, from budget-friendly hotels to luxurious ryokan.
Summary
Nanatsugama is a striking piece of natural art, showcasing the power of the sea. Whether you view it from the windy clifftops or from the deck of a boat bobbing at the mouth of a cave, it’s a sight that stays with you. The combination of the dark, dramatic cliffs and the vibrant water is a highlight of the Saga coastline. To get the full experience, take the boat tour from Yobuko, but even a simple walk in the clifftop park is a rewarding experience that connects you to the wild nature of this beautiful region.
Conclusion
For a memorable coastal adventure in Kyushu, Nanatsugama delivers a powerful visual punch. The key to a successful visit is planning: go by car, check the weather and boat schedules in advance, and combine your trip with the charms of Yobuko and Karatsu. It’s a place that reminds you of the slow, persistent artistry of nature, a perfect contrast to the fast-paced energy of Japan’s cities.
Sources / References
[1] Karatsu Tourism Association
[2] Asobo-Saga (Saga Prefecture Tourism Website)
Notes & Exceptions
•Information is current as of December 2025. Always check official sources for the most up-to-date information on boat tour times and prices.
•The boat tour is the only way to see the caves up close and potentially enter them. This is entirely dependent on sea conditions on the day of your visit.
•The narration on the boat tour is in Japanese only, but the visual experience transcends any language barrier.
Certainty Level
High
