Car park behind the church and on the road leading up to it (free)
Most of the walk is easy and well signposted (it follows the GR®131), taking a path through the forest and then along several craters before the junction at point 1, which leads directly up to Martin’s Volcano
Only the final ascent gets steeper and steeper, becoming very, very steep towards the end on volcanic gravel, but you can avoid it by taking the path on the left both on the way up and on the way back. The sign for the volcano isn’t on the GR®