I recommend purchasing the ‘Lanzarote Tour and Trail Map’ published by Discovery Walking Guides Ltd and available online (Amazon). It has marked walks (there is also a book to go with it) but it also shows lots of tracks that are not marked on any other maps. My husband and I have discovered lots of walks by using the map and often discover other tracks and paths which are not marked on the map. It is great to just get out there and explore. By doing so you can make your own walks of whatever distance you choose.