Mining railways, devoid of the glamour of passenger railways, tend to have a less than stellar existence. They generate no news and scarcely leave any photos or accounts behind, only their secluded routes through the mountains. This is the case of the mining railway which used to carry tons of iron ore from the pitheads at Arditurri to the port at Pasajes. It had a narrower gauge than conventional railways: 75 cm. This narrow gauge made it easier to negotiate the mountainous topography, while reducing building costs at the expense of lowering speeds, which, for obvious reasons, was not a key issue when transporting iron ore to the ships. However, that particular gauge was unusual, since the normal gauge used for mining railways was 60 cm, the gauge employed by the neighbouring Artikutza railway, for example. This line was conceived as the best way to take mineral ore from the Arditurri, on the west face of the Peñas de Aia crags, to the port at Pasajes.

The route from the mines runs gently downhill, ideal for a mining locomotive pulling laden wagons which could descend almost solely by gravity, and which only had to pull empty wagons, or wagons with mining equipment, from the port back up the mountain to the mines. The mines enjoyed a long history, from Roman times until, at the beginning of the 20th century, the Chavarri family of Basque business magnates acquired them and looked for a way of optimizing their exploitation. To that end they built this railway, dedicated solely to the transport of mineral ore, which was inaugurated in 1901.

The track went down to the port where there was a cantilever-type loading arm which enabled ore to be loaded directly from the railway wagons into the ships’ holds, although the ore could also be transferred to trains belonging to the broad gauge railway company, Compañía del Norte, which operated from the docks of this Guipuzcoan port. The mines shut down in the mid-1980s, but the trains had already stopped running in 1965, since the route of the new A-8 motorway effectively split the railway in two and the low volume of mine traffic that there was by then did not make it worth finding a solution to this problem.