Former Hokutan Yubari Coal Mine Mock Tunnel

Walking Inside Japan's Last Open Coal Mine Tunnel

The Former Hokutan Yubari Coal Mine Mock Tunnel is the only coal mine tunnel in Japan that visitors can still walk through on foot. Its 180-metre brick-arched passage begins in the hillside of Takamatsu in Yubari, Hokkaidō, descending on a gentle slope before levelling off into horizontal galleries. Partway in, the passage opens onto a reconstructed working face complete with a drum shearer and self-advancing roof supports. Continue past it and the gallery dead-ends against an exposed coal seam — black, faintly glossy, the same Yubari coal that Hokutan was hewing eighty years ago — that visitors are invited to touch with their bare hand.

This is no theatrical stage set. The passage was a working subsidiary of Hokutan's Tenryū Pit, refitted in 1939 to receive imperial inspection, and registered as a tangible cultural property of Japan on 18 October 2006. Today it sits at the heart of the Yubari City Coal Mine Museum and is a constituent asset of the "Tankōtetsukō" (Coal–Iron–Port) Japan Heritage.

From a 1888 Outcrop to an Imperial Inspection Tunnel

The colliery began with a discovery in 1888. Ban Ichitarō, an engineer dispatched by the Hokkaidō Government Office, traced an unusually thick outcrop along the upper reaches of the Shihorokabetsu River — three superposed coal seams of six, eight and ten shaku, totalling around seven metres in vertical thickness. The find now lies a short walk above the tunnel entrance, designated a Natural Monument of Hokkaidō and counted among Japan's hundred most significant geological sites. Within two years the Hokkaidō Colliery and Steamship Company — Hokutan for short — had begun driving its first workings into the seam, and Yubari's transformation from forested valley to northern colliery capital was under way.

The Third Pit was sunk into the same coal layer in 1900 and later renamed Tenryū-kō, the "Heaven Dragon Pit." The passage that today's visitors enter began as one of its subsidiary tunnels. In 1939, ahead of a visit by members of the imperial family, Hokutan refitted a section with a brick arch and a graded floor so that distinguished guests could inspect the workings without difficulty. The same gallery doubled as a training tunnel for the mine's underground rescue brigade, who practised navigating smoke, rubble and tight spaces in conditions close to those they would face in a real emergency below ground.

Each subsequent royal visit prompted further refinements. When Emperor Hirohito and Empress Kōjun arrived in 1954, a double-jib coal cutter was installed at the working face — the technology of the moment — and the passage took on roughly the form it has kept since. By the late 1960s the cutter had been replaced by a drum shearer paired with hydraulic walking chocks, the same equipment that was supporting production faces across Hokkaidō. When the colliery itself wound down and the Yubari City Coal Mine Museum opened in 1980, the passage became a permanent public exhibit. It joined the national register of tangible cultural properties in October 2006 under the criterion of "contributing to the historic landscape of the country."

Why This Tunnel Matters

Two facts set this tunnel apart from any other coal-mining heritage in Japan.

The first is its survival as a publicly walkable passage. Coal mines in Japan have been closing since the 1960s, and their underground workings have almost without exception been sealed, flooded or removed for safety. The Yubari Mock Tunnel is the country's last continuously preserved walk-in coal gallery — the only site where the public can stand inside the rock, look at the seam in place, and trace the descent that the miners themselves used to make. Coal-heritage parks in Iizuka, Ōmuta and elsewhere present surface infrastructure of great quality, but none retains an underground gallery that visitors can enter on foot.

The second is the assemblage of mining equipment preserved on its working ground. Where most industrial museums display extracted machines on plinths, the Mock Tunnel keeps a drum shearer, self-advancing roof supports, a double-chain conveyor and a roadheader installed in the positions they would have occupied during real extraction. One of the drum shearers, introduced in 1964, was kept in dynamic preservation — capable of being run for visitors — until 2024, and is, by the museum's account, the only example of its kind to have been maintained that way in Japan.

The 2006 registration cites "contribution to the historic landscape of the country." That is bureaucratic shorthand for a fairly grand role: a single 180-metre passage that stands in for an entire vanished industry, one that at its 1960s peak produced around twenty percent of Hokkaidō's coal output and supported a city of more than 117,000 people.

What to See on a Visit

A visit follows the descent that working miners knew. From the entrance the slope drops at a gentle gradient. The brick vault overhead is patched in places with reinforcing rolled-steel beams cut from old rail track — an improvisation typical of mid-twentieth-century pit engineering. Lighting is dim by design; too much heat or stray light is unhelpful to an exposed coal face.

A short way in, the passage opens onto the longwall coal face, the reconstructed kiriha. Two galleries, an upper uesoe drift and a lower gate drift, are connected by an inclined working face cut at roughly twenty degrees — the natural dip of the Yubari seam. The drum shearer hangs at the face; steel walking chocks support the roof at the same twenty-degree tilt; the conveyor runs beneath them to carry coal toward the gate drift. The whole scene is canted to one side, a faithful, slightly disorienting reproduction of how a real longwall would have been laid out. Visitors descend the face on a stepped walkway alongside the conveyor.

At the foot of the face, follow the gate drift to the left rather than the obvious exit on the right. The gallery dead-ends at a section where the coal seam itself is exposed in the wall — the eight-shaku bed, the middle of the three seams visible at the great surface outcrop above. The black coal is dull and matte under direct light, but trace it with a finger and individual layers come up to meet the touch, sometimes with the faint imprint of fossilised plant matter. Few experiences in Japanese industrial heritage are this physically direct.

The tunnel reopened in April 2025 after a six-year closure following a fire that broke out during welding work in 2019. The repair was supported by a hometown-tax crowdfunding campaign, and new fire-detection equipment has been installed throughout. A guided "mini-tour" of around fifteen minutes runs on the hour from 11:00 to 16:00 during the open season.

Around the Site

Above ground, the same museum hilltop holds the Yubari Twenty-Four-Shaku Coal Outcrop itself — the three exposed seams that began the entire story, designated a Natural Monument of Hokkaidō and listed among the hundred select geological sites of Japan. The cliff face stands just south of the museum building, a short walk from the tunnel entrance, and is freely viewable during museum hours.

Two further registered cultural properties of the Tenryū-kō complex stand within sight. The portal of the manway shaft and the portal of the materials shaft, both built in the same period from brick and concrete, complete the surface architecture of the pit. Together with the Mock Tunnel they form a compact group of "Tankōtetsukō" Japan Heritage assets.

For a broader reading of the coal-iron-port industrial story, the cities of Iwamizawa and Mikasa to the west, and the port of Otaru to the north, preserve other constituent assets of the same Japan Heritage route. Yubari itself is a quiet town now — its population peaked at about 117,000 in 1960 and is below 7,000 today — and the descent from museum hill down through the former mining settlements is its own kind of historical reading.