2018 September: Made it to the beach around 11am to find absolutely no-one there, heaven on earth. This beach is actually very north end of the Marathias beach - as mentioned before, you can come down from the top dead-end road. The beach is very natural. There is also the mud wall; you can have some cosmetic treatment if that's good for your skin (or not, I don't know). Later there was one local and another couple came, but no-one else. It's great.

South of Marathias, but still on the same stretch of beach, you can reach the hamlet of Agia Varvara by car from the main road Corfu - Kavos (turn southwest from the crossroads about the middle of the quite-new Perivoli by-pass, then fork right). This is a delightful corner (at least out of season) and there is a large stretch of empty beach beyond the cliff to the left where nude sunbathing is common. See it on Google Maps