Aoki Shima no Yado Kumano Bettei Nakanoshima is a unique hot spring resort located on the entire island of Nakanoshima, floating at the entrance to Katsuura Bay in Nachikatsuura, Wakayama Prefecture.
Known as a special island resort surrounded by the deep blue waters of the Kumano-nada Sea, the property operates as an entire-island, single-inn retreat. The only way to reach the island is by the inn’s private boat, making the short journey across the water feel like the beginning of an escape into another world.
Surrounded by the sea, Nakanoshima is blessed with abundant nature, a rich history, and plentiful natural hot spring water. The inn is also an excellent base for exploring the sacred heritage of Kumano, including the Kumano Kodo pilgrimage routes, Kumano Nachi Taisha Grand Shrine, and Seigantoji Temple.
Guests traveling to Kumano Bettei Nakanoshima first walk approximately 7 minutes from JR Kii-Katsuura Station to the Katsuura Tourist Pier, where they board the inn’s private boat.
The crossing takes only a few minutes, but the journey itself is part of the experience. From the boat, visitors can look back toward the town of Katsuura and enjoy views of Kinoshima and the scenic islands of Kii Matsushima.
As the boat approaches Nakanoshima, the peaceful resort surrounded by water gradually comes into view. With little traffic noise and the sounds of waves and birds replacing the bustle of everyday life, guests can begin relaxing even before they arrive.
Nakanoshima is a small island measuring approximately 68,000 square meters, with a circumference of about 1.7 kilometers. Located at the entrance to Katsuura Bay, the island was historically used as a place where ships could wait for favorable weather before continuing their journeys.
The island is surrounded by emerald-green waters and offers beautiful views of Kii Matsushima, a scenic area dotted with numerous islands and rocky formations.
In 1936, Nakanoshima was designated as a special protection area within Yoshino-Kumano National Park, reflecting the importance of its natural environment.
One of the greatest pleasures of staying here is the constant presence of the sea. Every guest room has an ocean view, with the waters of Katsuura Bay and the surrounding islands unfolding beyond the windows.
The signature attraction of Kumano Bettei Nakanoshima is the spectacular seaside open-air bath known as Kishu Chomon-no-Yu.
Built directly beside the rocky shoreline, the open-air bath faces the vast Pacific Ocean. The boundary between the bath and the sea seems to disappear, creating the extraordinary sensation of bathing almost directly in the ocean.
The bath is also famous for having been ranked No. 1 nationwide in the Nikkei Plus One ranking of spectacular baths, recognized for its breathtaking view in which the sky and sea seem to merge into one.
While soaking in the warm water, guests can listen to the sound of waves breaking against the rocks. In the morning, the rising sun appears above the horizon; in the evening, the ocean glows golden in the sunset; and at night, the bath offers a view of the star-filled sky.
Few bathing experiences combine natural scenery and hot spring culture quite so dramatically.
Nakanoshima is home to one of Japan’s relatively rare island hot springs. Six natural spring sources are found on the island, producing more than 700 tons of hot spring water per day.
The total flow reaches approximately 486 liters per minute, allowing the baths to be supplied entirely with naturally flowing spring water.
The spring is classified as a sulfur-containing sodium-chloride hot spring, with mildly alkaline and low-osmotic-pressure characteristics. Its sulfur content is traditionally associated with skin care, while the salt content helps the body retain warmth and moisture.
For this reason, the spring is popularly known as a “beauty hot spring” in Japan.
The spring has traditionally been associated with relief from a variety of conditions, including neuralgia, muscle pain, joint pain, frozen shoulder, lower back pain, sensitivity to cold, bruising, motor impairment, and reduced gastrointestinal function. It is also traditionally used for recovery after illness, relief from fatigue, and general health maintenance.
Sulfur-containing hot spring water is also commonly appreciated in Japan for its cleansing effect on the skin and its ability to leave the skin feeling smooth. These are traditional bathing benefits rather than medical guarantees, but they are an important part of the appeal of sulfur hot springs.
In addition to the main bathing areas and open-air baths, the resort offers private open-air baths where guests can enjoy a more intimate experience.
These private baths are ideal for couples, families, or anyone who would like to enjoy the hot spring while taking in the ocean view in a more secluded setting.
The island also has a natural hot spring foot bath called Kukai-no-Yu. It is a pleasant place to stop during a walk around the island, allowing visitors to rest their feet while looking out across the magnificent Pacific Ocean.
Nakanoshima has walking trails where guests can explore the island while enjoying seasonal flowers and coastal scenery.
The paths lead to a scenic viewpoint overlooking the Kumano-nada Sea. Standing there with the sea breeze on your face and the vast ocean stretching into the distance offers a wonderful sense of the scale and beauty of Kumano’s natural environment.
The island is also home to a monument inscribed with a poem by Bokusui Wakayama, a celebrated Japanese poet. When Bokusui visited Katsuura during the Taisho era (1912–1926), he was deeply moved by the scenery, and his connection with the area remains commemorated on the island.
Another highlight of a stay at Kumano Bettei Nakanoshima is its cuisine, which makes the most of the abundant seafood brought by the Kuroshio Current.
Dinner is served at Dining Kumano no Megumi, where guests can enjoy Japanese kaiseki cuisine prepared with fresh local seafood and seasonal ingredients.
Katsuura Port is one of Japan’s major ports for freshly landed tuna, and the local tuna is a particular specialty. Depending on the season and menu, guests can also enjoy spiny lobster, locally caught fish, and mountain produce from the Kumano region.
Breakfast features nourishing dishes incorporating local culinary traditions, offering a gentle introduction to the flavors of Kumano and a refreshing way to begin the day.
All guest rooms are designed with ocean views, allowing guests to wake up to the blue waters of Katsuura Bay and the surrounding coastal scenery.
The newer Nagi no Sho building was created around the concept of “the luxury of silence.” Its refined spaces provide a peaceful environment where guests can slow down, look out over the calm sea, and enjoy a deeper sense of relaxation.
The combination of quiet surroundings, ocean views, and the natural sound of the sea creates an atmosphere that feels far removed from everyday life.
Kumano Bettei Nakanoshima is also an excellent base for exploring the cultural and spiritual heritage of the Kumano region.
The Kumano Kodo, a UNESCO World Heritage pilgrimage network, as well as Kumano Nachi Taisha Grand Shrine, Seigantoji Temple, and Nachi Falls, can all be visited as part of a sightseeing trip from the Katsuura area.
After walking historic pilgrimage routes and visiting sacred sites, guests can return to the island, soak in a spectacular oceanfront hot spring, and enjoy fresh seafood from the surrounding waters.
This combination of pilgrimage, nature, hot springs, and cuisine makes a stay at Nakanoshima particularly appealing for travelers who want to experience several sides of Kumano in one journey.
Aoki Shima no Yado Kumano Bettei Nakanoshima is one of the signature hot spring resorts of the Nanki-Katsuura area, offering an extraordinary experience on an island that can only be reached by private boat.
Its spectacular oceanfront open-air bath, abundant naturally flowing hot spring water, ocean-view rooms, island walking trails, and cuisine featuring seafood from the Kuroshio Current all come together to create a truly special retreat.
Surrounded by the natural beauty and spiritual heritage of Kumano, guests can listen to the waves, soak in the hot springs, watch the changing colors of the sea, and simply enjoy the passage of time.
For travelers visiting Nachikatsuura, Kumano Bettei Nakanoshima offers a rare opportunity to experience Japan’s traditional hot spring culture in an extraordinary island setting—a peaceful escape where the ocean itself becomes part of the journey.