Gaztelugache is an islet in the Biscayan town of Bermeo, Basque Country.

It is linked to the mainland by a bridge with two arches.

On the island there is a hermitage dedicated to San Juan that dates from the 10th century, although some discoveries date from the 9th century.

This hermitage was built on the remains of a castle attached to the Kingdom of Navarra and which was besieged, without being taken, by the Castilian troops.

Together with another small neighboring island, that of Aqueche, it forms a protected biotope, which extends from the town of Baquio to Cape Machichaco in Bermeo, in the Bay of Biscay.

The tradition of going up and ringing the bell three times to make a wish or drive away evil spirits is joined by others. When the Bermean fishing boats go out to fish they usually make several turns to port and starboard so that the saint will give them luck. Women who suffer from a problem related to fertility usually come to this place in the belief that the Saint will help them solve this problem. The stairwells, identified as the footprints of San Juan, are given different healing powers, to benefit from them you have to put your feet in them looking for them to heal the calluses or leave hats, scarves or chapels to heal the headache.

Tradition has it that San Juan Bautista came to land at this point on the Basque coast, leaving his footprints on the rock in four different places: at the San Juan arch in the town of Bermeo itself, next to the Itsasalde farmhouse, in the top of Burgoa and finally next to the Ermua farmhouse, it was placed in 1982.

It also tells that in the caves of the rock the inquisition locked up those accused of witchcraft.