This greenway is another example of a route born from railway variants. On 28 May 2012, Euskal Trenbide Sarea opened a new double-track tunnel on the line leaving Donostia/San Sebastián towards Bilbao, replacing a winding stretch of track that had been in service since 9 April 1895.

That short section was part of the Elgoibar–San Sebastián railway, a narrow-gauge line built by a company that lasted only briefly. After a turbulent financial process, it merged with the Durango–Bilbao, Durango–Elorrio, and Durango–Zumárraga railways, consolidating all these Bizkaia–Gipuzkoa lines under a single company: Ferrocarriles Vascongados (Basque Railways), officially formed on 1 July 1906. As part of Ferrocarriles Vascongados, this section saw thousands of trains of all kinds until 1972, when a severe financial crisis forced the company to abandon operations. The line was then taken over by FEVE, in a process very similar to what was happening across Spain at the time. State management lasted only a decade: in 1982, most of the Basque narrow-gauge network, including this section, was transferred to Eusko Trenbideak. Today, what was once a busy railway corridor is a peaceful greenway, while just a few metres away trains still speed through the new tunnel.