As you drive west out of Puerto Rico (direction Maspalomas) and pass through Arguineguin, just before approaching the motorway there's a fork to the right to take you on to the road C812. Going this way for 10 minutes will bring you to the bay of Santa Agueda and several small, not-that-well-discovered beaches. These beaches are known mainly by the locals and few tourists but do get very, very busy Saturday and Sunday as the island's population from the north comes down to enjoy them. The beaches are popular with nudists though each is mixed, "clothes off" isn't essential!
The number 32 salcai bus also passes by these beaches though stops are few and far between so you may have a hefty walk to get to the beach you want, best to go by car.
First beach you come across is all rocks and gravel and not that easy to get to, it's called El Lomo Galeon. My advice, drive past that for 2 minutes and you'll see the next :-
Playa Llanillo

As with most of the beaches in this bay, once you see a beach you like it's a case of finding level land next to the road where you can pull off and park. Just past this beach to the left is a place you could park or just before to the right there's space for a couple of cars. 5-10 minutes of pretty easy walking down there from your parked car. The beach is around 300 meters long, mainly sand though gravel further back from the water.
Los Bigotes

The second of the more appealing beaches you come to and this one has a bus stop close by and is also very easy to spot from the road as you drive just a few meters away from it. There's space for about 10 cars to park just past it on the right or space on the left for a lot more right opposite. The beach itself is only about 100 meters long with little sand, mainly gravel. At the end of the beach though there's another 100 meters of flat, more comfortable rocks.
Playa Triana

This is literally at the north end of Los Bigotes. You wouldn't really notice one stopping and another starting but just in case anyone tries to pull me up on it .....
Montaña de Arena

This beach and the next, Montaña de Arena are my favorites.Not as easy to walk to nor visible from the road makes these beaches more popular with naturalists. Each of them is very sandy and easy to get in and out of the water so popular with families too.
As you drive past Los Bigotes, you can see part of the bay next to the road, carry on for another 5 minutes but look out for a large, flat area of land to your right about 100 meters back from the road. You'll see it well in advance as it's usually got a fair few cars already parked there. You'll see a track leading from the road to the parking area, there's space there for over a hundred cars. Once parked, head down towards the sea and to the left and you'll find a path that runs along the cliff top going left. Follow this path for 10 minutes of careful walking and you're at the beach. Very sandy beach and the hill behind is all sand too (hence the name, "Mountain of Sand").
Las Carpinteras

Much easier to reach than Montaña de Arena but still a hefty walk. The easiest way is to pass the parking for Montaña de Arena and watch out for the next flat area of land to your right, again there'll probably be cars already parked on it. There's a couple of tracks off the road to get to the parking, take either and drive as far away from the road as you dare. The further you go, the worse the track; you'll see what I mean when you get there. Once parked, walk along the path that takes you over the hill and down to the left. At the top of the hill you'll see the beach and the path down to it.
If you drove past this parking area for another 1km or so round the next corner, you'll see another dirt track off the road. You won't see the parking area though this track does lead you to it and from there, it's an easy 2 minute walk to the beach. Chances are though you'll miss the turning!
