At the foot of the Fort of San Marko in Errenteria

Park in a small car park south-east of the centre of Errenteria (if there are no spaces, continue south; 150 metres further on, on the left, there is a larger car park).

(S/E) Head west along the road that climbs. Further on, take the concrete track that rises to the left. A little further on, walk past some odd-looking huts (which are actually private kennels for hunting dogs). Then look out for the blue, yellow and green markings, which you should follow until you reach a fork.

(1) Follow the dirt track that branches off to the right.

(2) At a crossroads, you’ll find signposts. Follow “San Marcos” to the right, following the same markings. The path now climbs steeply. You’ll reach a junction at the foot of a pidgeon hunting hut,

(3) Take the path on the left, which winds its way through the forest like a rollercoaster. After a steep descent, you’ll reach a concrete track.

(4) Turn left onto it. After about 150 metres, take the stony track on the left, still in the forest.

(5) Find and take the earthen staircase on the right, which descends steeply. After the two houses below, continue to follow the same markings.

(6) Further on, at a junction, head down to the right until you reach another junction after crossing a small stream.

(7) Head up to the left. At the top, rejoin the path you took on the way there.

(2) Head straight ahead and return to the car park by following the route in reverse (S/E).

At the end of the walk, you can drive to the Fort, where there is a lovely picnic area.