A Mystical Landscape Hidden in a Residential Neighborhood
One of the most surprising aspects of Ukishima-no-Mori is how easily it can be reached. The site is only about a six-minute walk from Shingu Station.
Visitors can walk through the urban surroundings and suddenly find themselves facing a quiet, densely vegetated wetland. Despite the houses and roads nearby, stepping into the forest creates an immediate change in atmosphere. The peaceful water, lush vegetation, and unusual floating landscape can feel like entering another world.
Wooden walkways and bridges have been installed within the site, allowing visitors to explore the forest safely. Crossing the bridge toward the floating island is itself a memorable experience, almost as if you were traveling to a mysterious island hidden in the middle of the city.
The Secret Behind the “Floating” Forest
The secret of Ukishima-no-Mori lies in the peat that forms its foundation. Peat is an organic soil created when dead plants accumulate in waterlogged environments and decompose only very slowly.
The peat at Ukishima-no-Mori is particularly lightweight and capable of holding large amounts of water. This allows the peat layer to remain buoyant on the surface of the pond. A layer of water also exists between the upper and lower peat layers, allowing the island to function as a vast natural floating mass.
In the past, it was said that the entire island could move during typhoons and strong winds. Local stories even describe the ground shaking when people stamped their feet on the island, adding to its mysterious reputation.
Today, urban development, sediment accumulation, and other environmental changes have caused much of the island to come into contact with the bottom of the pond, so it no longer moves dramatically. Nevertheless, parts of the island have been observed to rise and fall slightly in response to changes in water levels.
A Natural History Dating Back to the Jomon Period
The formation of Ukishima-no-Mori is closely connected to the long geological history of the region, stretching back to the Jomon Period of ancient Japan.
During the early Jomon Period, sea levels were higher than they are today, and much of the area around present-day central Shingu was covered by an inland bay. As the coastline gradually moved farther away, the bay transformed into wetlands and marshes.
Natural levees and coastal sand ridges helped preserve the wetland for an extended period, while groundwater continued to flow into the area. Dead vegetation accumulated without completely decomposing, gradually turning into peat and creating the foundation of the floating island.
Research suggests that some of the peat layers forming the present island were deposited around the early Edo period. The relatively rapid accumulation of peat compared with many other peatlands is another distinctive feature of this remarkable environment.
A Rare Community of Plants from Cold and Warm Climates
An Extraordinary Botanical Ecosystem
One of the main reasons Ukishima-no-Mori has been designated a National Natural Monument is its exceptionally unusual plant community.
Plants normally associated with cooler regions, such as large sphagnum moss and Japanese chain fern, coexist here with plants adapted to warmer climates, including southern fern species. The presence of plants with such different climatic preferences in the same small wetland is extremely unusual in Japan.
This rare mixture of cold-climate and warm-climate plants gives Ukishima-no-Mori significant academic value. Surveys conducted between 1999 and 2000 recorded 125 plant species belonging to 64 families.
The forest includes a variety of trees and plants, such as Japanese cedar, bayberry, Japanese winterberry, azaleas, and kobanmochi. Despite its relatively small size and urban surroundings, the floating island supports a surprisingly rich ecosystem.
The fact that plants normally associated with highland environments can be found in a low-lying urban wetland makes this site particularly fascinating to botanists and nature enthusiasts.
The Legend of Oino and the Snake’s Cave
A Traditional Tale Connected to the Floating Forest
Ukishima-no-Mori is also associated with an old local legend known as the “Legend of Oino.”
According to the story, a young woman named Oino once lived near the island with her father. One day, the two crossed onto the floating island to collect firewood. When they stopped to eat, they realized that they had forgotten their chopsticks.
Oino went deeper into the forest to find a suitable branch to use instead. However, she did not return. Concerned, her father went looking for her and discovered that his daughter was being swallowed by a gigantic snake.
Although her father desperately tried to save her, Oino was eventually pulled into a mysterious bottomless pool known as the “Snake’s Cave.”
The legend later became associated with Japanese literature. It is said to have influenced “The Lust of the Snake,” a story in Ueda Akinari’s Ugetsu Monogatari, an important collection of Edo-period tales. The story was also adapted into a play by modern Japanese novelist Tanizaki Junichiro, giving the legend a lasting place in Japanese literary culture.
A Sacred Place Connected to Shugendo
Ukishima-no-Mori is more than a natural attraction. It has also been regarded as a place of spiritual significance for centuries.
Before the modern era, the area was reportedly used as a place of religious training by the Kamikura Hijiri, a group of ascetic practitioners associated with Kamikura Shrine. In Shingu, an important center of Kumano religious traditions, the mysterious forest was considered a sacred place closely connected with the spiritual power of nature.
The forest’s connection to Kumano’s tradition of nature worship helps explain the special atmosphere that many visitors experience today. Even without a detailed knowledge of its history, the quiet wetland and ancient vegetation create a strong sense of mystery and tranquility.
Environmental Conservation and Restoration
Protecting a Fragile Urban Wetland
Ukishima-no-Mori has faced considerable environmental pressure as the surrounding city has developed. Falling groundwater levels, wastewater entering the wetland, declining water quality, and sediment accumulation have all threatened the ecosystem.
During the latter part of the Showa period, plants such as large sphagnum moss and Japanese chain fern declined significantly, while some cedar trees also died. The spread of non-native plants became another concern, increasing the risk of losing the site’s unique natural environment.
In response, local authorities and researchers began implementing a range of conservation measures. These included preventing wastewater from entering the wetland, introducing groundwater, removing accumulated sediment, and improving water quality.
These efforts have produced encouraging results. Improvements in water quality have been accompanied by the expansion of sphagnum moss, recovery of Japanese chain fern, and the germination of young cedar trees.
Research and conservation work continue today, helping ensure that this extraordinary wetland can be preserved as a valuable natural heritage site for future generations.
Nature Observation and Nearby Attractions
Discover the Forest with a Local Guide
Visitors can also explore Ukishima-no-Mori with nature observation guides registered with the Shingu Tourism Association. Learning about the plants, geological formation, legends, and history while walking through the site can provide a much deeper understanding of its significance.
The forest is also conveniently located near several important attractions in Shingu. These include Kumano Hayatama Taisha Grand Shrine, the Sato Haruo Memorial Museum, Jofuku Park, and the Nishimura Memorial Hall.
Combining a visit to Ukishima-no-Mori with these cultural sites offers travelers an excellent opportunity to explore the history, spirituality, literature, and natural beauty of Shingu.
Access and Visiting Information
Location
Ukishima, Shingu City, Wakayama Prefecture 647-0014, Japan
Getting There
The site is approximately a six-minute walk from JR Shingu Station, making it an unusually accessible natural attraction for a wetland located in the heart of a city.
Tips for Visitors
The wooden walkways are designed to make the area relatively easy to explore, but the wetland environment can become slippery, particularly after rain. Visitors are advised to wear comfortable shoes with good grip and take extra care in wet conditions.
The appearance of the forest and its plants changes with the seasons, so each visit can offer a slightly different experience. Visitors should also help protect this fragile ecosystem by staying on designated paths and respecting the natural environment.
Experience the Mystery of Ukishima-no-Mori
Ukishima-no-Mori is an extraordinary place where geology, botany, history, folklore, and Japanese spirituality come together. A floating peat island supporting a rare mixture of plants is remarkable in itself, but its location in the middle of Shingu makes the experience even more surprising.
For travelers exploring the Kumano region, a visit to this hidden natural monument offers a chance to experience a quieter and more mysterious side of Wakayama. Walk across the bridge, explore the forest, learn about its ancient origins, and discover the legends that have surrounded this unusual landscape for generations.
Ukishima-no-Mori is a place where the natural history of Japan, traditional beliefs, and the beauty of a living wetland can be experienced in one unforgettable setting.