Nokobiura Windbreak | A Dam-Like Barrier Between the Sea and Village Life

On the northwestern side of Naru Island, the coastal road leads toward the small community of Okushi.

There, filling the gap between two steep hills, stands a massive wall of earth and stone.

This is the Nokobiura Windbreak.

From the village side, its broad slopes resemble a rock-fill dam built deep in the mountains. Climb a little higher, however, and the landscape changes dramatically.

Beyond the embankment lies Nokobiura—a narrow cove framed by rugged cliffs and opening directly onto an endless blue sea.

Strong wind rises from the coast. Behind you, fields, houses, and the sheltered landscape of Okushi stretch across the opposite side of the ridge.

The structure is not a dam, and it does not hold back water.

It was built to hold back the powerful northerly winds that sweep through this narrow valley toward the village.

Part protective structure, part dramatic viewpoint, and part geological field site, the Nokobiura Windbreak is where the natural forces that shaped the Goto Islands meet the practical ingenuity of the people who live here.

A Massive Wall Between the Sea and the Village

The Okushi area lies in northwestern Naru Island.

Calmer waters and the settlement extend to the south, while Nokobiura faces the more exposed sea to the north. Between them, the land narrows into a slender neck surrounded by steep hills.

This narrow valley was created along a geological fault.

Its shape acts like a corridor, gathering winds from the northern coast and directing them toward the village.

Typhoons in late summer and autumn, along with cold winter winds, have long been a powerful presence in the lives of local residents.

The windbreak was built across this natural corridor to weaken those winds before they reached homes and farmland.

Seen from below, the embankment appears almost to be part of the mountain.

Seen from above, it becomes clear that it stands directly between two very different landscapes: the exposed open sea on one side and the inhabited village on the other.

Excavated Rock from a Tunnel Became Protection

The story of the windbreak is closely connected to the Enmeiji Tunnel, which carries the road toward Egami Church and the western settlements of Naru Island.

Before the tunnel opened, travel between the island’s central area and communities such as Egami and Okushi was more difficult.

The Enmeiji Tunnel, measuring approximately 770 meters, entered service in 1994 and became an important part of everyday transportation on the island.

Its construction produced a large quantity of excavated earth and rock.

Rather than transporting all of this material away, it was piled into the fault-formed valley at Nokobiura and used to create the windbreak.

One public works project therefore produced two forms of protection for island life.

The tunnel improved access across the mountain, while the excavated material became a barrier against the wind.

What might otherwise have been treated simply as construction spoil was transformed into a structure that protects the nearby community.

Climb a Little, and the Ocean Suddenly Appears

A short climb beside the windbreak leads to an open view over Nokobiura.

The sea appears between steep, green-covered cliffs, extending toward the horizon without another large island immediately blocking the view.

Below, the broad earth-and-stone embankment seems to stretch across the valley like a dam holding back the ocean.

It is this unusual perspective that gives the site its striking visual impact.

The most memorable part of the experience, however, may not be the scenery alone.

It is the wind.

Conditions can change significantly from day to day. Even when the village side feels relatively calm, the top of the embankment may be exposed to powerful gusts rising from the sea.

On some days, official tourism information warns that the wind can be strong enough to make standing difficult.

Feeling that force directly makes the purpose of the structure immediately understandable.

Turn toward the sea, and you face the exposed natural environment.

Turn back toward Okushi, and you see the homes and fields the windbreak was built to protect.

Standing between the two offers one of the clearest examples on Naru Island of how local life has adapted to the island’s terrain and climate.

A Fault Beneath the Windbreak

Nokobiura is important not only because of its unusual protective structure.

It is also one of the few places where visitors can observe evidence of the fault activity that helped divide the Goto region into its principal islands.

Geologists interpret the Nokobi Fault as a northwest–southeast-trending normal fault with a left-lateral component.

It is associated with tectonic forces that affected the region around seven million years ago, when faulting helped form the channels between the major islands and contributed to the deeply indented coastline seen today.

At Nokobiura, the fault includes a zone of fractured and crushed rock approximately 50 meters wide.

Differences between the rock layers on either side suggest that vertical movement along the fault may have reached several hundred meters.

The valley occupied by the windbreak is therefore not an ordinary dip between two hills.

It follows a major weakness in the earth created by tectonic movement.

The same geological forces that helped give Naru Island its narrow bays and complex outline also created a natural passage for strong winds.

Much later, people filled part of that passage with excavated rock to protect their community.

Black Volcanic Glass Along the Coast

The coast around Nokobiura also contains deposits associated with obsidian.

Obsidian is a dark, glass-like volcanic rock created when silica-rich magma cools rapidly.

Because it breaks into extremely sharp edges, it was widely used to produce knives, arrowheads, and other tools from Paleolithic times through the Jomon period.

Obsidian tools have been discovered elsewhere in the Goto Islands.

Although Nokobiura contains substantial deposits, no artifacts have yet been definitively identified as having been made from Naru Island’s obsidian.

This raises an intriguing question.

Was the material difficult to reach? Was its quality unsuitable for toolmaking? Or have objects made from it simply not yet been identified?

Recent geological research has added another layer to the story.

A study conducted in 2025 and 2026 reported that some of the dark, band-like volcanic intrusions at Nokobiura, once described as obsidian, have altered over time into a rock known as pitchstone.

The same study suggested that a major volcanic event may have occurred around Nokobiura approximately 12 million years ago.

This remains a developing scientific interpretation, but it reveals that the quiet coast may preserve evidence of both major volcanic activity and later fault movement.

The relevant outcrops lie along rugged shorelines rather than a maintained sightseeing path.

Visitors should not attempt to reach them casually or alone. A local geoguide or organized field visit is the safest and most rewarding way to explore the geology.

Where Geology and Island Life Meet

A geosite is not valuable only because it contains an unusual rock or visible fault.

Its deeper appeal lies in the relationship between the earth and the people who live on it.

At Nokobiura, fault movement created a narrow valley.

That valley concentrated winds from the sea.

People established their homes and fields on the more sheltered side of the ridge.

A modern tunnel was later built to improve access across the island.

The material excavated from that tunnel was then used to block the wind passing through the fault-formed valley.

Geology shaped the land.

The land influenced where and how people lived.

And people responded by creating a new human-made landform within the natural one.

The Nokobiura Windbreak is therefore more than an unusual piece of civil engineering or a dramatic photo spot.

It is a visible record of the continuing relationship between Naru Island’s geology, climate, infrastructure, and everyday life.

Visit Together with Egami Church

The Nokobiura Windbreak lies beyond Egami Church in the northwestern part of Naru Island.

Visiting the two places together reveals very different sides of the island.

At Egami Church, visitors encounter a small wooden church adapted to the humid environment of a coastal valley and built through the collective efforts of local believers.

At Nokobiura, they encounter a vast earth-and-stone structure built to protect an exposed settlement from the wind.

One is a place of prayer.

The other is a practical barrier against the weather.

Yet both demonstrate the same underlying principle: people on Naru Island have learned to work with the landscape rather than ignore it.

The white-and-blue church surrounded by trees and the rugged windbreak facing the open sea form a striking contrast.

Together, they reveal both the gentleness and the raw power of Naru Island.

Before You Visit

The Nokobiura Windbreak is an outdoor scenic and geological site with no admission fee or fixed visiting hours.

Visit during daylight, when the access route and surface of the embankment can be clearly seen.

The slope and upper areas include loose gravel, exposed earth, stones, and uneven ground. Wear sturdy walking shoes with non-slip soles.

Wind is the most important safety consideration.

Conditions at the top may be much stronger than they appear from the village side. Secure hats, phones, cameras, and loose belongings.

Do not climb when gusts are strong enough to affect your balance.

Stay well away from steep edges, and do not visit during typhoons, thunderstorms, heavy rain, high waves, or other severe weather.

Official spot information does not list a dedicated visitor parking area, toilet, shop, or other tourist facilities.

The surrounding roads serve local residents. Park only where it is safe and permitted, without blocking traffic, driveways, agricultural access, or emergency vehicles.

Prepare drinking water and use toilets around Naru Port before traveling to the site.

The coast where faults and volcanic rocks can be observed has poor footing and includes rocky shoreline sections.

Do not descend to the shore without appropriate experience or local guidance. Never remove rocks or damage an outcrop.

Ferries to Naru Island may be delayed or canceled because of weather and sea conditions.

Rental cars and taxis are limited, so arrange your ferry and island transportation together before traveling.