Sandaili

Sandaili is a cave in the Araotz valley, part of the municipality of Oñati in Gipuzkoa, in the Basque Country. Tucked inside this large cavity is a small hermitage, the Ermita de San Elías, making the site one of the more unusual stops in the region — a place where geology, religion, and folklore all meet in the same rock.

Where is Sandaili located?

The cave sits in Araotz, one of the outlying districts of Oñati, right along the road connecting the town to the Sanctuary of Arantzazu. Visitors reach the entrance from a small parking area, and the walk in takes only a few minutes, which makes Sandaili accessible even for people who aren't regular hikers. Because of its position on the Arantzazu road, many travelers combine a stop here with a visit to the sanctuary itself.

Why is there a hermitage inside the cave?

Local legend holds that San Elías (Saint Elijah) lived as a hermit inside the cave after being expelled from his home village for openly criticizing his neighbors' vices. Rather than return to the community, he chose a life of seclusion within the rock shelter, and over time his story was passed down through generations in the Araotz valley, becoming part of the area's oral tradition.

Why is the name Sandaili debated among researchers?

The cave's name is not as straightforward as it first appears. Researcher Martín Mendizábal proposed that "Sandaili" does not derive from "San Elías" at all, but from an older form, "Santa Ylia" — itself a Christianized version of a pre-Christian deity named Yvulia. According to this theory, the ritual once practiced in the cave has Celtic roots, and giving the site a saint's name was a way for the Church to absorb an older cult into a Christian framework.

What ritual took place inside the cave?

Within the rock is a stone basin known locally as the "aska." Tradition holds that women unable to conceive would come to the cave to wash their hands in it or bathe in the water collected there, believing the ritual would help them have children. Practiced across generations, this custom is often cited as evidence that the site served a sacred function long before Christianity arrived in the region.

What else draws visitors to Sandaili?

Beyond its layered history and legend, Sandaili stands out simply as a natural space — the scale of the cave interior and the way the small hermitage sits tucked into the rock give it a distinct character. The site has also picked up a literary following: Basque author Ibon Martín used it as a setting in one of his crime novels, drawing readers curious to see the real backdrop of the book. Despite this, Sandaili remains relatively low-key compared with more heavily visited spots in Gipuzkoa, which for many visitors is part of the appeal — it can be explored without crowds.

Frequently Asked Questions

Where exactly is the Sandaili cave? In the Araotz valley, part of the municipality of Oñati in the province of Gipuzkoa, along the road that connects Oñati with the Sanctuary of Arantzazu.

What is inside the cave? A small hermitage known as the Ermita de San Elías, along with a stone basin called the "aska" linked to old fertility rituals.

Where does the name Sandaili come from? One theory holds it doesn't come from "San Elías" but from "Santa Ylia," a Christianized form of an older, pre-Christian deity called Yvulia tied to Celtic-rooted rites.

How do you get to the cave? From a small parking area along the road to Arantzazu — the walk to the entrance takes just a few minutes.