Jinata Onsen: Hot Spring Guide & Visitor Access (Tokyo)

Shikinejima, one of the Izu Islands reached by ferry south from Tokyo, is home to Jinata Onsen, a wild spring that wells up on the coast in its natural state. The water rises in a V-shaped cleft that looks as if it were split by a machete, and as the tide rises and falls it mixes with seawater to reach a comfortable temperature. The brownish, iron-rich water and the openness of the rock-and-sea setting give it a force found nowhere else.

Highlights

• A striking landscape in a V-shaped cleft that looks split by a blade
• A natural wild bath whose temperature shifts with the tide
• A distinctive brownish water rich in iron
• An open soak that feels at one with the sea

Enjoying the Seasons

Since this is a seaside wild bath entered in a swimsuit, the warmer seasons are the most enjoyable. In summer pair it with sea bathing, and in spring or autumn a soak in the clear air while listening to the waves is something special. Because the temperature changes greatly with the tide, choosing the hours around high tide gives you just the right warmth.

Access and Basic Information

• Location: Shikinejima, Niijima Village, Tokyo (along the coast)
• Access: about a 30-minute walk from Nobushi Port, with a steep downhill stretch of stairs along the way
• Use: swimwear is required, free to use and open 24 hours
• Spring quality: regarded as an iron-bearing spring; the water emerges hot and reaches a comfortable temperature when mixed with seawater
• A natural wild bath with no changing rooms or showers

Practical Travel Notes

• Recommended season: since you bathe in a swimsuit, the warm months from early summer to early autumn are best, overlapping the sea-bathing season.
• Recommended time: the temperature depends on the tide, and the stretch from low toward high tide is said to be the easiest to enter, so always check a tide table.
• Time needed: about 1.5 to 2 hours for the round trip from the port and the soak, as part of a day on Shikinejima.
• Real spots nearby: on the same island are the seaside Ashitsuki Onsen and Matsugashita Miyabiyu baths, along with Tomari Beach.
• Budget sense: the spring itself is free, so the ferry fare and island lodging are the main costs.

A Quick Tip

The footing is slippery and there are no changing rooms, so it helps to bring something to throw on over your swimsuit and a pair of sandals. There are also hours when the tide makes bathing impossible, so check a tide table before heading out. Because it is a hot spring in its natural state, watch the weather and the waves and take care for your safety as you enjoy it.

Practical Information for Your Visit

• Use: Free of charge, available 24 hours. This is not a hot spring facility operated by Niijima Village but a "noyu" (wild open-air bath) that wells up naturally on the shore. There is no caretaker or lifeguard on site
• Spring quality: According to the Shikinejima Tourism Association, it is an iron sulfide spring. The source temperature is about 80 degrees, so you look for a spot where it has mixed with the incoming seawater and bathe there. It is also known as the "Naika no Yu" (bath of internal medicine)
• Bathing etiquette: A swimsuit must be worn (it is a mixed-gender open-air bath). Soap and shampoo cannot be used
• Facilities: There is no changing room and no shower. Toilets are at the parking area
• Access: From Takeshiba Pier in Tokyo to Shikinejima it is about 3 hours by high-speed jet ferry, or about 8 and a half to 10 hours by large passenger ship (information from the Shikinejima Tourism Association; depending on the season the large ship also calls at Yokohama Osanbashi Pier). It is about 3 and a half hours by ferry from Shimoda, or 35 minutes by plane from Chofu to Niijima plus about 15 minutes on the connecting boat Nishiki. On the island it is about a 30-minute walk from Nobushi Port, with a steep flight of steps down just before the hot spring
• Safety notes:
• The source water is extremely hot, at about 80 degrees. Before getting in, check the temperature at the "yukagen no ana" (temperature-checking hole) and choose a place where it has mixed with seawater to a comfortable temperature. Never put your feet into the hot spots
• You go down a steep slope and steps to reach the shore, and the area around the pools is wet rock. Bring non-slip sandals or shoes and do not walk barefoot
• The temperature of the water depends greatly on the tide, and there are times when bathing is not possible depending on the tide level and the state of the waves. Check a tide table for the times of low and high tide before you set out
• Do not go near the spot during high waves or bad weather. Avoid bathing alone, and allow yourself plenty of time
• There is almost no outdoor lighting at night. If you visit then, be sure to bring a light
• What to bring: swimsuit, something to throw on over it, towel, drinks, sandals, a light

* Shikinejima also has Ashitsuki Onsen and Matsugashita Miyabiyu (both seaside hot springs where swimsuits are worn), as well as the indoor "Ikoi no Ie."

(Sources: official website of the Shikinejima Tourism Association and others. As of July 2026)