Tokyo Island, with its hot springs and pristine beaches

This article appears in Tokyo Weekend Vol. 4.
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The air here smells of the sea, salty and invigorating, mixed with the strong earthy smell of sulfur from the hot springs. A jagged cliff stands out on the coastline, its jagged outline visible against the sky. The rough feel of the rock underfoot gives a sense of the island’s raw beauty.

While Tokyo is world-famous for its bustling streets and towering skyscrapers, few are aware of the islands south of the metropolis. Shikine-jima is a volcanic island in the Philippine Sea that is part of the Izu Islands, which is governed by Tokyo. Although Shikine-jima is one of the smallest islands in the region, measuring just 12 kilometers in circumference—small enough to leisurely walk around in just two to three hours—it is a treasure trove of natural wonders.

This island may be small in size, but it’s rich in resources. Shikinejima is home to numerous natural hot springs, where a fusion of seawater and geothermal activity creates mineral-rich pools that nestle along the coast. These hot springs are a testament to the island’s volcanic origins, and each one offers a unique experience due to the interplay of natural forces.

Here are some must-sees on your next trip to the island. (Please note that swimsuits are required at all outdoor onsens.)

Jintian Hot Spring

The onsen is reached by walking down a long rocky staircase lined with colorful wildflowers—pink, purple, and yellow—that contrast with the grayish-white rocks scattered on the ground. These rocks are called kougaseki, or fire-proof rocks, a type of volcanic pumice that is native to two places: the Izu Islands and the Italian island of Lipari.

The name Jida Onsen is rich in meaning. Breaking down the kanji, “地” means “ground” or “land” and “奈” means “axe.” The terrain surrounding this hot spring looks as if it was split open by an axe, creating a striking V-shaped valley.

The water source of Jitian Onsen is a combination of hot spring water and seawater. As a result, the temperature and mineral content of the hot spring water changes with the tide and time of day, creating a unique blend of water. At low tide, the iron-rich water that flows into the beachfront rock pools is boiling hot, and as the tide rises, the water temperature gradually decreases and mixes with the cooler seawater, creating a comfortable bathing experience.

The water itself has a distinctive reddish-brown colour, indicative of the presence of iron sulfide. This mineral-rich composition has earned the Jitian Onsen the nickname “Internal Medicine Hot Spring” among locals. Jitian Onsen is said to be effective in treating a range of ailments, including gastrointestinal disorders, neuralgia, rheumatism, cold sensitivity and gynecological problems.

In a ranking of open-air baths curated by renowned hot spring sommelier Fuyuto Noguchi, Chifu Onsen topped the list in the east. This recognition speaks volumes about its charm and the unique experience it offers to those who descend down the long staircase to the warm and inviting waters.

Full-term spa

Ashitsuki Onsen is located on the coast of Shikinejima, next to the local hot springs. Rocks and volcanic structures form a natural basin where geothermal water gathers and radiates steam from the surface. The hot spring is famous for its clear water, which is unique among the many hot springs on the island.

Ashitsuki Onsen takes its name from local legend. It is said that long ago, an injured sea lion (ashika in Japanese) found solace in this hot spring. Day after day, the sea lion would return to the rock pool and soak in the soothing, mineral-rich waters. Islanders saw the animal’s amazing recovery and soon realized the healing properties of the hot springs. Since then, Ashitsuki Onsen has become famous for its effectiveness in healing cuts, scrapes, and other skin ailments.

While local hot springs are known as “internal medicine hot springs,” Ashitsuki Onsen earned the nickname “surgical hot springs” because it was believed to help heal external injuries. In an era when medical facilities were scarce, island residents would come to Ashitsuki Onsen for recuperation.

In 1987, the area around Ashitsuki Onsen was selected as one of Japan’s 100 best beaches, with its white sand and green pines. As one might expect from the list of awards, the area, commonly known as Shikine Matsushima, features stunning pristine sandy beaches and black pine trees, which contrast with the hot springs dotted throughout.

Azuki Onsen is a free open-air bath that offers a unique experience as visitors soak in the hot springs while appreciating the pristine beauty of the rocky coastline. Similar to local hot springs, the water temperature at Azuki Onsen changes with the tides, but the water temperature tends to be milder, making it more flexible. If a rock pool is too hot for you, simply move to another pool further up the shore where the seawater blends better with the hot spring.

Matsushita Masayu

Matsushita Masayu is an artificial bathhouse that perfectly blends natural and artificial elements. Its spring water is taken directly from local hot springs, and visitors can enjoy the soothing embrace of the hot springs without being restricted by tidal changes and bathing time restrictions.

The facility is divided into two parts. One part mimics a human field with a series of rock pools along the coast, while the other part is an artificial pool with a sea view. The former provides a pristine, unfiltered hot spring experience, while the latter provides a steady, comfortable bathing experience, ensuring visitors can enjoy a soak at any time of the day.

While the local hot springs are known for their healing waters, walking down the long rocky stairs can be daunting, especially for the elderly and small children. Matsushita Masayu was built to provide a more convenient alternative. It is the only hot spring facility of the three hot springs that is directly accessible by car, making it the most convenient option for visitors of all ages. Since Matsushita Masayu’s water is nearly the same quality as the local hot springs, it has the same healing properties whether you are looking to relieve muscle pain or skin conditions, or just want to relax.

As the day fades, the setting sun casts a golden glow over the rugged rocks of Shikinejima, turning them into natural sculptures of light and shadow. The sky takes on stunning shades of orange and pink, which are reflected on the water, creating a mesmerizing tableau. As night falls, the sky darkens and a field of stars emerges, unobstructed by the lights of the city. The night sky here is vast, shimmering and stunningly clear. For onlookers tucked between the rocks and the calm waves, it feels like the stars are falling from the sky – and these onsen are one of the best places to see them.

More information

Shikinejima is accessible from Takeshiba Pier in Tokyo by high-speed ferry, which takes 3 hours, and by large ship, which takes 10 hours. There is also a 3.5-hour ferry from Shimoda. Alternatively, visitors can take a 35-minute flight from Chofu Airport to Niijima, and then take a 15-minute ferry to Shikinejima.

For more details, please visit the official website of Shikinejima.

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