Do I need special equipment to visit Ioki Cave?

Waterproof footwear or rain boots are essential as the trail through the cave and canyon can be damp and slippery. You can borrow rain boots from the community center near the parking area, though availability is not guaranteed, especially for larger sizes. Bring your own waterproof shoes if possible.

How long does it take to explore the cave?

A complete walk through the cave and canyon typically takes between 20 to 50 minutes depending on your pace and how much time you spend observing the ferns and waterfalls. The cave itself is 40 meters long, with the trail continuing through the canyon to reach the waterfalls.

Is Ioki Cave suitable for children and elderly visitors?

The site is accessible to visitors of all ages, though the natural, unpaved trail can be uneven and requires basic mobility. Young children and elderly visitors should be supervised as the path follows a stream with rustic bridges and can be slippery in places.

Can I visit Ioki Cave without a car?

Yes, the cave is easily accessible by train. Take the Gomen Nahari Line to Ioki Station, then walk for just 5 minutes to reach the cave entrance. The train journey from Kochi City takes approximately 1.5 hours. Parking is also available if you prefer to drive.

Kochi

Ioki Cave, Aki

4.3 (1150)Tourist AttractionPoint Of InterestEstablishment

Last updated Mar 29, 2026

Ioki Cave is a natural sea cave located in Aki City, Kochi Prefecture, on the island of Shikoku, Japan. The cave is a 40-meter long natural tunnel that was carved out by waves millions of years ago, with walls that still display fossilized shellfish, remnants from when the entire area was submerged beneath the sea. The geological formations date back approximately three million years, making this site a window into the region's ancient marine past.

The cave's fern colony was designated as a National Natural Monument in 1915, recognized for its exceptional biodiversity. Approximately 40 species of ferns, predominantly tropical varieties, thrive on the cave walls and throughout the canyon beyond. The temperature remains around 20 degrees Celsius year-round, creating ideal conditions for this rare concentration of fern species. The dense vegetation covering the steep canyon walls creates an atmosphere that visitors often compare to scenes from animated films.

Walking through Ioki Cave takes visitors from the dimly lit tunnel entrance into a lush canyon where a small river connects three waterfalls hidden among the green fern forest. The complete walk through the cave and canyon typically takes 20 to 50 minutes depending on pace. The trail follows the stream over rustic bridges, with the largest waterfall located at the end of the route, where water collects in an emerald pool. The unpaved, natural trail can be damp and uneven, so waterproof footwear is essential.

The cave entrance is located just a 5-minute walk from Ioki Station on the Gomen Nahari Line, which is approximately a 1.5-hour train ride from Kochi City. Visitors can borrow rain boots from the local Ioki community center near the parking area, though availability varies and larger sizes may not be in stock. Optional guided tours are available for ¥1,000 per person, though these are conducted only in Japanese. The site is open year-round and accessible to visitors of all ages. Parking is available across from the cave entrance.

Phone

+81 887-34-8344

Website

www.akikanko.or.jp

Overview

Address

117 Ioki, Aki, Kochi 784-0045, Japan

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Frequently Asked Questions

Traveler reviews

Do not miss this! Yes, it’s wet and muddy and you scramble up narrow tracks and over stepping stones but that’s half the fun. The other half is the beautiful natural environment. When you get to the top you can walk via road back to the carpark which was easier than making the way back downhill. The walk took us through rice paddies with the ocean in the background. Allow about an hour.

Nat M

May 2, 2026

Amazing cave right off the main road. There is a parking lot and information center with rain boots that you can borrow. You can hike it for free but you can also make a reservation for a guided tour for a small fee. The cave and trail is very wet, so I would recommend wearing waterproof shoes or borrowing some boots. The hike itself is quite short and doesn’t require any specific gear or preparation. It’s very pretty and still quite green even in the winter.

Very lovely surprise! Interesting cave that leads to a valley. Nice short walk. Recommended.

Ioki Cave feels like stepping into a fantasy world. After passing through the narrow cave entrance, you emerge into a calm canyon draped in vivid green moss, with a clear stream winding along the trail. Towering bamboo arches overhead, filtering gentle light and adding to the sense of wonder. The path is short and mostly flat, but slow down—every corner reveals new textures, colors, and sounds. Your reward at the end is a graceful waterfall cascading into a shaded pool, the perfect spot to pause and soak in the atmosphere. If you are anywhere near Aki City or Muroto, make time for this hike. It is peaceful, photogenic, and unforgettable—truly one of Kochi’s hidden gems.

A hidden green paradise, very clear water and fresh green moss. A beautiful hidden cave with fresh water. Highly recommended to come in the morning, and suggest not come after rain as the water would be moving very fast and deep, it will be quick dangerous if you do not have full suitable gear to walk in during the rainy day. They have water shoes for borrowing next to the car park which is very convenient. However the place is quite far away from the city, you have to drive an hour from the city centre. Please be aware a that some animals are living in this cave eg snack and bats.