An Ancient Cedar More Than 800 Years Old
Iwakura Chichi-sugi is estimated to be approximately 800 years old. The tree reaches around 30 to 40 meters in height and has a trunk circumference of approximately 11 meters.
At a height of roughly 3 to 4 meters above the ground, its massive trunk divides into around 15 major trunks. From these branches and trunks hang numerous unusual aerial roots known as kasui-kon.
More than 20 of these hanging roots can be seen, with the longest reaching approximately 2.6 meters. Their distinctive shapes resemble pendulous breasts, giving the tree its Japanese name, “Chichi-sugi,” literally meaning “breast cedar.” The roots create an extraordinary appearance, as though the ancient tree is extending countless living forms back toward the earth.
The Origin of the Name and Local Beliefs
The unusual shape of the hanging roots gave rise to the name Chichi-sugi. For generations, local people have regarded the tree as a sacred deity associated with breast milk and nursing.
Traditionally, people have visited the sacred tree to pray for an abundant supply of breast milk. A religious ceremony is held every year on April 23, and the tree has long been protected as a sacred tree by the local community.
This connection between an ancient natural landmark and local faith makes Iwakura Chichi-sugi culturally significant as well as visually spectacular.
A Unique Shape Created by a Harsh Natural Environment
The cedar grows in an unusually challenging environment. The ground consists largely of rocks formed from collapsed lava, with only a thin layer of soil that has limited ability to retain water.
Under these conditions, the tree cannot easily obtain sufficient moisture through its roots underground. It is thought that the development of its unusual hanging aerial roots may be an adaptation that helps the tree capture moisture from the surrounding air.
While many cedar trees can develop aerial roots, it is extremely unusual to find an individual with such a large number and such remarkably long roots. Its distinctive form is a striking example of how living organisms can adapt to demanding environments over long periods of time.
Cool Air Emerging from a Natural “Wind Cave”
Another fascinating feature of the area around the tree is the surprisingly cool air that can be felt even during summer. This phenomenon is associated with a geological feature known as a “wind cave,” or fūketsu.
A wind cave occurs when cool air moves through gaps between rocks or underground cavities and emerges at the surface. Around Iwakura Chichi-sugi, countless basalt boulders are piled together, creating natural passages through which air can circulate.
Air cooled within the rock-filled spaces flows outward through these gaps, creating a noticeably cooler environment around the tree. During the hot summer months, the refreshing air provides a welcome natural retreat.
A Forest Shrouded in Mist
After rainfall, the forest can become enveloped in mist, transforming the surroundings into an especially atmospheric landscape. Moss-covered rocks, ferns, ancient trees, and drifting mist combine to create scenery that feels almost like a setting from a traditional Japanese folktale.
The appearance of the forest changes with the weather, season, and time of day. This constantly changing atmosphere is one of the special attractions of visiting Iwakura Chichi-sugi.
Geology Revealing the Formation of Mount Daimanji
The rocks surrounding Iwakura Chichi-sugi originated from basaltic lava that erupted approximately 4.5 million years ago. As the lava cooled, it developed regular fractures known as columnar joints. Subsequent erosion, weathering, and rock collapse gradually transformed these formations into the boulder-covered landscape visible today.
The area also features a geological structure known as a cap-rock formation. Hard basalt layers overlie softer sedimentary layers, and differences in their resistance to erosion have contributed to repeated rockfalls and landslides.
These geological processes helped create the unusual terrain and natural wind caves around the ancient cedar. The tree therefore stands within a landscape whose present form is the result of millions of years of volcanic activity and erosion.
How to Experience Iwakura Chichi-sugi
A visit to Iwakura Chichi-sugi is about much more than seeing a giant tree. The surrounding forest, unusual geology, cool air, silence, and atmosphere are all part of the experience.
Visitors can take their time observing the massive trunks and hanging roots while listening to the quiet sounds of the forest. The cool air emerging from the rocks provides another memorable sensation, particularly in summer.
After rainfall can be an especially atmospheric time to visit. When mist rises through the forest, the ancient cedar takes on an even more mysterious appearance. The area is also well suited to nature observation and photography, although visitors should take care not to disturb the natural environment.
Enjoy the Forest Responsibly and Safely
The road leading toward Iwakura Chichi-sugi passes through mountainous terrain, with some narrow and unpaved sections. Drivers should take particular care when dealing with oncoming vehicles and changing road surfaces.
The forest floor can also become slippery, especially after rain. Wear sturdy, comfortable footwear and walk carefully when exploring the area.
Because this is a fragile natural and sacred environment, visitors should help preserve its character by taking all rubbish with them and avoiding the collection of plants, rocks, or other natural materials. Respecting the quiet atmosphere of the forest is an important part of the experience.
Access to Iwakura Chichi-sugi
Iwakura Chichi-sugi is approximately 60 minutes by car from Saigo Port. From the port, follow the roads toward Mount Daimanji and continue along the forest road toward the site.
The journey leads through the deeply wooded interior of Dogo Island, offering beautiful natural scenery along the way. The drive itself provides a glimpse of the remote mountain landscape that characterizes the island.
An Ancient Tree Where Nature and Faith Come Together
Iwakura Chichi-sugi is far more than an enormous cedar. It is a place where ancient nature, unusual geology, and generations of local faith come together.
After surviving for approximately 800 years in a harsh rocky environment, the tree stands today as a remarkable symbol of endurance and adaptation. Its multiple trunks and extraordinary hanging roots give it a presence unlike that of an ordinary forest tree.
Surrounded by cool air, ancient rocks, moss, and mist, the tree creates an atmosphere that feels far removed from everyday life. For travelers exploring the Oki Islands, a visit to Iwakura Chichi-sugi offers a quiet opportunity to encounter one of Dogo Island’s most mysterious natural treasures and experience the deep connection between people and the landscape.