The San Adrian Tunnel

The most strategic gap

At about one thousand meters above sea level there is a gap that crosses a rock uniting the gorgeous mountain ranges of Aizkorri and Aratz and so the provinces of Álava and Guipúzcoa. This scenic gap is what gives shape to one of the most representative natural frontiers of the Basque Country.

Plan your getaway to San Adrian Tunnel

The San Adrián Tunnel is located within the Natural Park of Aizkorri. The closest access by car is a forest track that begins from Etxegarate Port. It’s a narrow road with some parking lots but generally it’s not easy to leave your car there. There is a stunning hike following the path; the landscape is really beautiful. There are also two towns close to the tunnel from which day trips are usually organized; Zalduondo (in Álava) and Zegama (in Guipúzcoa). Other nearby towns that can be visited during your getaway to San Adrian Tunnel are Zerain, Segura and Idiazabal.

Do you want to visit this place?

Throughout history, armies, kings, merchants and pilgrims have crossed the San Adrian Tunnel. As a crossing point, its origins go back to antiquity, to Roman times. At that time, the road linked Astorga with Bordeaux, still guiding the visitor’s steps on both sides of the opening. Since the 11th century the tunnel was mostly used as the natural road of communication between the region of Llanada Alavesa and the Guipuzcoan valley of the River Oria; a transit point between Castile and the rest of Europe.

In 1290, Pope Nicolás IV awarded privileges to pilgrims, passers-by and beggars who on the day of his feast, would visit the hermitage of San Adrián, inside the tunnel. In its heyday the place was endowed with facilities, a tavern, stables and a permanent guard among others. The hermitage even had a mayor’s office, and one of his mayors even boasted of being one of the most important people of all of Europe, of the most distinguished rich men and nobles of the continent.

Because of the narrow exit of the tunnel the majority of visitors had to bend over and uncover their head. Moreover, the passage was not free of charge as evidenced by the remains of the old medieval customs, which, on the Guipuzcoa side, are nowadays the entrance to the pass.

The tunnel is also one of the key points of the initial point of the inland Way to Santiago. Since the Alava pilgrimage route came up as an alternative to the coastal route (which sometimes turned out to be too dangerous because of the partisan fights and banditry, especially in Guipúzcoa and Vizcaya between 14th and 15th centuries), the pilgrims took advantage of the ancient Roman road to travel from the Basque coast towards the city of Vitoria. Due to the intense darkness inside the tunnel, it soon became known as the “Mouth of Hell”.

Entrada al Túnel de San Adrián
Entrada al Túnel de San Adrián

In 1502 princes Phillip I called the Handsome or the Fair and Joanna known as the Mad, passed through the tunnel during their trip from Flanders to Castile. Both stopped in the hermitage of the tunnel to act as godparents of Felipe de Lazcano (named after the prince), son of the famous sailor and military Juan de Lazcano, escort of Phillip I, born in the area.

The improvements made communication routes during the 18th century were subtracting traffic to San Andrián Tunnel, which would be abandoned in 1851, when the highway crossing the massif through the port of Etxegarate was inaugurated. Nowadays it is a natural first-rate tourist resource.

From Guipúzcoa, the nearest town to the tunnel is Zegama, located on the banks of the River Oria. It is reached by climbing a steep and high trail that runs on a slope through Sierra de Aizkorri. The entrance is under a stone arch attached to the remains of a medieval wall, which were the old customs offices where travelers had to pay.

Before entering, we clearly see the Hermitage of San Adrián on a rock inside the tunnel, on the right. This hermitage was built in 1883 above an older one, probably of the 11th century. In its pile Felipe de Lazcano, godson of the princes Phillip the Handsome and Joanna the Mad, was baptized in 1502.

Ermita de San Adrián
Ermita de San Adrián en el interior del túnel

The tunnel is not very extensive. About fifty meters separate both ends, perfectly visible each from one another. The exit towards Álava narrows to approximately two meters height giving the tunnel a false impression of cave, if observed from the outside. The pleasure of crossing the tunnel of San Adrian has a payoff that makes the effort absolutely worth your while as it gives you the opportunity to enjoy a unique natural wealth.

On the southern slope there is the old mountain refuge of Miqueletes, from which the Guipuzcoan provincial guard tried to stop smuggling and livestock theft in the 19th century. If you continue on the road to Álava you will get to the town of Zalduondo.

Practical Data


42° 56′ 6″ N, 2° 18′ 55″ W


About half an hour walking from the tunnel,  you can park in a turn within the forest track.


1100 m

Other nearby destinations...

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