Oñati, Autonomous Community of the Basque Country, Spain
Aizkorri-Aratz is 15,919 hectares of limestone straddling the border of Álava and Gipuzkoa, protected as a natural park since 2006, and it contains the highest ground in the Basque Country: Aitxuri, at 1,551 metres. Underneath the bare grey tops it is mostly beech and oak forest, and between the two sit long meadows that are grazed rather than mown.
The grazing is the part first-time walkers underestimate. The horses, cattle and sheep up here are not behind wire. They are on the paths, in the shade of the trees you were heading for, and entirely unbothered by people. A walker who spent several days in the park in August 2021, posting on TravelFeed as @dresden and @dresden.theone, put it plainly: wherever you walk around, you find freed horses, cows and sheep feeding on the meadows.
What follows is built from those three write-ups, checked against the Basque Government's own park information.
What Aizkorri-Aratz actually is
The park straddles the watershed between the Cantabrian and Mediterranean sides of the peninsula. It spans eleven municipalities: Aretxabaleta, Asparrena, Barrundia, Eskoriatza, Legazpi, Leintz-Gatzaga, Oñati, San Millán/Donemiliaga, Zalduondo, Zegama and Zerain. Roughly four fifths of it lies in Gipuzkoa, the rest in Álava.
The summits are modest by alpine standards and steep by local ones. Aitxuri tops out at 1,551 metres, Aizkorri itself at 1,544, and Aratz, the other mountain in the park's name, at 1,443. That is the entire ceiling of the Basque Autonomous Community, stacked into one massif.
One small thing worth flagging, because it shows how the sourcing here works: @dresden's write-up calls it a 16,000-hectare park. The official figure is 15,919. He rounded, and he was right to within half a percent, which is a good sign for everything else in the post.
The beech forest makes its own weather
The sharpest observation in any of these posts is about the trees. The big beech and white oak stands, @dresden writes, create their own weather inside the forest, sometimes producing a very fine and cool drizzle. Anyone who has walked under old beech knows the effect: the canopy holds moisture and lets it go slowly, so the woods stay wet long after the sky has cleared.
The practical read: bring a shell even in August. His photographs are dated 6 August, high summer, and the woodland in them is soaked green, with moss climbing the trunks and the rocks either side of the path. Above the treeline the problem inverts, to open grass ridges with nothing to shelter behind, so a light waterproof and a warm layer both earn their weight on the same walk.
The horses are not fenced in
These horses are raised for meat, so somebody owns them, but they graze freely in the mountains and, as @dresden puts it, spend their whole lives that way. Nobody moves them off the trail for your convenience. His account of walking through a herd is the most useful thing in the three posts, partly because he is honest about being nervous. The breed is native to the Basque Country. The animals are smaller than most horse breeds but wide, strong and short-legged, and, in his words, not afraid of humans at all, which does not help towards being a little afraid of getting kicked when you have to go through the paths they feed on.
That is the situation to plan for: twenty-odd animals holding the shade beside the track, foals among them, and your route running straight past. The etiquette is unglamorous. Slow down, go wide rather than straight through, and never put yourself between a mare and a foal. Feeding them is the one thing to avoid outright, because an animal that learns to expect food from walkers stops giving them room.
Look up as well. The Basque Government's tourism service records the park as holding the largest griffon vulture colony in Gipuzkoa, and @dresden lists a large colony of vultures among the animal life he met without going looking for it.
Betizu and terreña, the cattle nobody wanted
The cattle have a better story than the horses. @dresden.theone's post on the two protected breeds lays out why they are wandering loose: their owners voluntarily abandoned them decades ago, because they produced less than the Swiss Alpine and French cattle being imported at the time. By 2006 only 450 animals of these breeds were counted. They survived at all because in 1975 a shepherd and his son introduced one bull, three cows and two calves before the breeds went under, and reserves on both the Spanish and French sides of the Basque Country have been rebuilding the population since.
They are semi-wild now and treated as a genetic reserve. The folklore is better still: betizu are held to guard treasure in the caves where the goddess Mari lives, which is the sort of detail that makes a herd of cows on a hillside considerably more interesting than it looked ten minutes earlier. The same post also records a terreña cow bellowing across a valley and another answering through the echo, a few kilometres apart, which is the kind of thing you only notice standing still.
Behaviour around cattle is the same as around the horses, with one addition: walk around a herd lying on the path rather than waiting for it to get up.
Saint Adrian's tunnel and the road through the mountain
The one piece of history worth planning a walk around is Saint Adrian's tunnel, a natural pass through the rock linking Álava and Gipuzkoa. A paved road runs through it. It was probably laid in the 16th century, though most of what survives dates from the 18th, and it carried both the Camino Real and the pilgrim route to Santiago. It is worth going out of your way for, if only because the crossing goes through the mountain instead of over it, which tells you how much traffic this range once had to take.
The other landmark is the sanctuary church at Arantzazu, above Oñati, which stands over a deep gorge on the Gipuzkoan side. It is also one of the three places the park runs an information point, which brings us to the gates.
Three ways in: Arantzazu, Araia and Zegama
The park runs three official information points, and picking the right one shapes the day more than picking the route does. Arantzazu, above Oñati in Gipuzkoa, is the one attached to the sanctuary and the obvious base for the Gipuzkoan side. Araia sits on the Álava flank. The third, Aizkorriko Ataria, is in the hamlet of Anduetza at Zegama, at the eastern end. All three are run as park information offices, so they are the place to confirm which marked routes are currently open before you commit to one.
Basing yourself at the entrance rather than day-tripping is worth the extra night, and @dresden's argument for it is the practical one: he stayed several nights in a hotel above the valley at the very entrance of the park, which meant walking from the door and picking his weather window rather than driving up into whatever the morning happened to be doing. All three of his write-ups come from that one base, and the photographs in them are dated across two consecutive days.
When to go
The community evidence here is a single summer visit, so treat it as one data point rather than a season-by-season verdict. What it does establish is that the first week of August is no guarantee of dry feet, and that the herds are on the high meadows at that point in the year, at around 1,000 metres. Nothing in these three posts says anything about the park in winter, and on a limestone massif topping 1,500 metres that gap is worth respecting rather than guessing at.
For anything time-sensitive, meaning route closures, whether a marked circuit is passable, or opening times at the three information points, ask the park directly rather than trusting a figure on a page. The Basque Government's official park listing carries the current contacts for all three, and the Wikipedia article is a reliable summary of the boundaries and the history of the pass.
Pairing it with the coast
Aizkorri-Aratz sits inland, and a mountain day pairs naturally with a coastal one. The same walker climbed Mount San Anton on the Getaria peninsula, the headland known locally as the mouse, which is the short coastal counterpart to a day on the ridges. West of Bilbao, @txatxy timed the metro out to Plentzia at exactly 43 minutes, running every half hour. A beach town you can reach without a car makes an easy recovery day after the herds and the drizzle. More of what TravelFeed writers have covered is collected on our Spain destination page.
FAQ
Where is Aizkorri-Aratz Natural Park?
In the Basque Country in northern Spain, on the border between the provinces of Álava and Gipuzkoa, roughly four fifths of it on the Gipuzkoan side. Oñati and Zegama in Gipuzkoa and Araia in Álava are the towns with official park information points.
What is the highest mountain in the Basque Country?
Aitxuri, at 1,551 metres, inside this park. Aizkorri, which gives the park half its name, is close behind at 1,544 metres, and Aratz reaches 1,443.
Are the loose horses and cattle in the park dangerous?
They are not aggressive, but they are unfenced, unafraid of people and frequently standing on the path. @dresden's honest note is that being kicked while squeezing past feeding horses is a real worry. Give them space, walk around rather than through a herd, and keep well clear of mares with foals.
Can you walk through Saint Adrian's tunnel?
Yes. It is a natural pass through the rock carrying a paved road that linked Álava and Gipuzkoa, probably built in the 16th century with most surviving remains from the 18th, and it formed part of both the Camino Real and the Camino de Santiago. Check current access at one of the park information points before planning a day around it.
How big is Aizkorri-Aratz Natural Park?
15,919 hectares, or about 159 square kilometres, declared a natural park in 2006. It covers eleven municipalities across two provinces.
