Nanatsugama: Magnificent Sea Caves Created by the Rough Waves of Genkai Sea

Nanatsugama: Natural Art Carved by the Rough Waves of Genkai

"Nanatsugama" is located on the coast facing Genkai Sea (Genkainada), northwest of Karatsu City, Saga Prefecture. It is a collective term for 7 sea caves formed by ocean erosion in cliffs of columnar jointing (structure of hexagonal basalt columns arranged) approximately 20 to 25 meters high. Designated as a National Natural Monument, it lies within Genkai Quasi-National Park.

The Seven Sea Caves Carved by Rough Waves

The greatest highlight of Nanatsugama is the seven mysterious caves lined along the cliff. These were carved over an immense span of time as the rough waves of the Genkai Sea eroded the columnar jointing of basalt formed by volcanic activity. The rock surface of regularly arranged hexagonal columns, and the sight of waves drawn into the dark depths of the caves, overwhelm the viewer.

Viewing from Sightseeing Boat and Observation Deck

There are two ways to enjoy Nanatsugama. One is riding the sightseeing boat "Ikamaru" departing from Yobuko Port to approach the caves from the sea. Shaped like a squid-fishing boat, it can advance near the cave mouths when waves are calm, offering a close-up view of the cliffs and caves. The other is looking down from the observation deck and walking paths developed on the cliff top, where the contrast of the vast Genkai Sea, the sea spray against the cliffs, and the green grassland forms a superb view.

Access and Basic Information

Access to Nanatsugama is convenient by car. Drive along the coastal road from central Karatsu; a parking area, observation deck, and walking paths are developed on the cliff top. The sightseeing boat "Ikamaru" departs from "Marinepal Yobuko" at Yobuko Port. The fare is a guideline of 2,000 yen for adults (junior high and above) and 1,000 yen for children (elementary). Boats run roughly once per hour and the ride takes about 40 minutes. On rough sea days, entry into the caves may not be possible or service may be suspended, so check the sea conditions in advance.

Practical Travel Notes

Boats can enter the caves more easily from spring through autumn, when the sea is relatively calm. In the morning, light shines in more readily, revealing the beautiful shadows of the caves. Allow about half a day to enjoy both the boat ride and the observation deck at a relaxed pace. It pairs well with the Karatsu and Yobuko area sights such as Yobuko Morning Market, Yobuko Bridge, Kabeshima Island, Niji no Matsubara, and Karatsu Castle. Yobuko is also known for live squid sashimi, so enjoying port-town gourmet after the cruise is a classic plan.

A Word of Advice

The cliff top is often windy, so a jacket brings peace of mind. The view from the observation deck can be enjoyed for free, but the sightseeing boat is strongly recommended to feel the caves up close. The boat can rock, so if you are prone to seasickness, prepare motion-sickness medication. Experience the dynamic natural artistry carved by the rough waves of the Genkai Sea from both sea and land.

📚 Sources

This article is edited based on tourism information from Karatsu City and Yobuko, guidance from Marinepal Yobuko, which operates the sightseeing boat Ikamaru, and published materials on the Natural Monument designation of Nanatsugama and Genkai Quasi-National Park. Boarding fees and schedules may change, and on rough-sea days entry into the caves may be impossible or service suspended, so please confirm the operator's official information and the day's sea conditions before visiting.

Visitor Checklist

• Estimated time: About half a day to see both the boat and the lookout; the Ikamaru cruise takes about 40 minutes
• What to bring: It is often windy atop the cliffs, so a jacket helps; boats can rock, so bring motion-sickness medicine if concerned, and keep cash for the fare
• Suggested route: Look down on the seven sea caves from the clifftop lookout and walking paths, then approach them from the water on the Ikamaru boat departing from Marinepal Yobuko; combine with the Yobuko Morning Market, Niji no Matsubara, or Karatsu Castle
• Weather: From spring to autumn the sea is calmer and boats can enter the caves more easily, and mornings offer light that shows the caves' shadows beautifully