I don’t know that area too well but I know about access rights here… you can go where you want to EXCEPT for the natural parks, there’s no right to roam in most of those. Sorry sidyid, that’s not correct for most of the parks, you shouldn’t venture off the wide paths.
Having said that. Sidyid is correct and bikers are god here. Everyone loves us 🙂 The most likely thing you will find if you are caught where you’re not meant to be is people cheering you on to ride stupid stuff! There are areas where this isn’t the case though… some environmentally sensitive areas where we shouldn’t be and wouldn’t be welcome so unless you know the area you should err on the side of caution.
Also, in parts of spain there are special police for the forests who won’t be at all happy if you offer them a bribe!!! If you do that though please take a photo and send it to me 🙂
Learn spanish for “I’m lost” and smile and you’ll be right. Take a surfboard or hire one at least, this coast is amazing for surfing.