The long south western end of Fuerteventura has a low desert separating the east and west coasts. Starting from the populated east and south side at Costa Calma this route crosses the desert and comes to the wild roadless north and west side.
Your first difficulty is to cross the FV-2 which is a motorway in this area, and had a substantial fence which would be seriously difficult to cross. Study the track and you can see we used two crossing places. We recommend the north east one. The other is a road underpass which essentially makes no provision for walkers.

As you leave the road behind you enter the desert. The day we were doing it we saw probably 10 other people crossing.
As of 2019 there are a multitude of informal dirt tracks going mostly coast to coast. The park authorities want people to stick to tracks to avoid disturbing the wild life.
By following these we gradually gained height. Towards the end of the outward leg and near the crest of the isthmus we came across the GR131 walking trail which has red and white markers.

Eventually and quite suddently the coast comes into view. There are cliffs made of successive layers of lava and sometimes sands into which the wind driven waves crash.

At points this can be really spectacular and give you a serious drenching.
In the background of the above picture you can see the astonishing line of the mountains of the Peninsula de Jandia crowned by Pico de la Zarza at aound 807m

Heading south west we found the easy walking gradually petered out. The above picture was taken from near where we finished.
We returned by climbing the scarp and picking up a track marked with blue markers that led back towards Costa Calma.
A fantastic day. Beware that is a very exposed wild place without much shelter from sun or wind.