Aizkorri Trek from San Sebastian: Basque Peaks & Sanctuary

Climb to the roof of Gipuzkoa and descend through the San Adrian tunnel

A private full-day trek from San Sebastian to Mount Aizkorri, the highest peak in Gipuzkoa, led by an experienced guide who speaks English or Spanish. The route passes the avant-garde Sanctuary of Arantzazu, climbs 800 meters through meadows and limestone crags where latxa sheep graze, and offers a choice of descent: either retrace the ascent with your guide or descend solo through the San Adrian tunnel, a natural cave known to locals as the gateway to the underworld. Hotel pickup, a picnic lunch of local cheese and cured meats, and a glass of wine at the end are included.

Step-by-step itinerary

Full-day trek to Mount Aizkorri

• Pick up from San Sebastian
• Introduction to Basque Highlands history
• Visit Sanctuary of Arantzazu
• Ascend Mount Aizkorri through meadows and forests
• Enjoy panoramic views and local lunch
• Descend via San Adrian tunnel or same path
• Return to car and enjoy local wine

The experience

You're picked up from your San Sebastian hotel in the morning and driven to the trailhead with time for your guide to explain the day ahead and the history of the Basque Highlands. The first stop is the Sanctuary of Arantzazu, a 1950s structure that rises above craggy rocks and is considered one of the world's most avant-garde religious buildings: Basque artists like Eduardo Chillida and Jorge Oteiza shaped its design. From there, the ascent of Mount Aizkorri begins in earnest.

The path starts through open, treeless pastures where latxa sheep graze, then steepens into rocky limestone formations as you climb. Peregrine falcons, griffon vultures and booted eagles often circle overhead. At the summit, after 17 kilometers of hiking and 800 meters of elevation gain, you stop for lunch: Idiazabal cheese, cured sausages, ham and tuna from a nearby port, eaten with views across the Basque Country. The descent is where the day splits. You can retrace the route with your guide, or go solo through the San Adrian tunnel: a historically significant natural cave that cuts through the mountain and emerges on the opposite side. If you choose the tunnel, your guide equips you with a walkie-talkie and detailed directions so you can experience both faces of the peak and the ancient passage itself. Either way, you return to the car where your guide offers a glass of local wine before the drive back to San Sebastian.

What’s included

• Hotel pickup and drop-off in San Sebastian.
• private experienced guide and driver.
• all transportation costs including petrol, parking and tolls.
• picnic lunch with Idiazabal cheese, cured sausages, ham and tuna.
• glass of local wine at the end of the hike.

Before you book

Days and timesEvery dayDeparts at 09:00

Book up to1d before

AgesAdult (18 and older) · Child (12 to 17 years) · Under 12: can't be booked

GroupPrivate

Live guideEnglish and Spanish

Meeting point and pickupHotel pickup included.

Cancellation and refundsFree cancellation up to 24 h before the start. After that, no refund.

Prices and times updated 14 days ago

Good to know

Moderate physical effortInfant seats availablePets welcomePublic transport nearby

Operated by Ikusnahi Tours

Is this one for you?Pick this if you want a private guide who speaks your language (English or Spanish) for the full day, so communication flows naturally throughout.

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Top questions

What languages is the tour guided in?

Live guide in English and Spanish.

Can children come?

Yes. Ticket types: Child (12 to 17 years). Children under 12 can't be included in the booking.

What is the Sanctuary of Arantzazu and why is it on this hike?

The Sanctuary of Arantzazu is a 1950s religious structure built above craggy rocks and designed by leading Basque artists including Eduardo Chillida and Jorge Oteiza. It stands as one of the world's most avant-garde religious buildings and sits on the route to Mount Aizkorri, making it a natural cultural stop before the ascent begins.

Can I choose how to descend from Mount Aizkorri?

Yes. You can either descend the same way you climbed up with your guide, or go solo through the San Adrian tunnel, a natural cave that passes through the mountain and emerges on the opposite side. If you choose the tunnel, your guide provides a walkie-talkie and all necessary information to navigate it safely.

What kind of sheep are grazing on the mountain, and why does the description mention them?

Latxa sheep graze the meadows and pastures on Mount Aizkorri. They are a local breed whose milk is used to make Idiazabal cheese, the most famous cheese in the region and one of the specialities included in your picnic lunch at the summit.

How much elevation gain is involved in this hike?

The hike covers 17 kilometers total distance with 800 meters of elevation gain. The ascent is gradual at first through pastures, then steepens as the path enters rocky limestone terrain near the summit.

What birds might I see during the climb?

Peregrine falcons, griffon vultures and booted eagles often glide above the rocky peaks of Mount Aizkorri, especially as you gain altitude and enter the more exposed limestone formations.