The Captain heard that there is a very nice place to swim nude on Sifnos, which has existed for a long time: the flat rocks below the village of Kastro. It is not suitable for families with children because it is not easy to get out of the water, but the place is one of the best in Sifnos. To get there, follow the steps from the top of the village to the small church near the sea (at the eastern end of the village). One contributor reports 60% nudists there, and apparently guide books say there are a lot of nudists there. But a 2002 report said there were no nudists right below the church on the cliff even if the Rough Guide says that it is the place where naturists sun themselves.

2023 June: Visited here (the rocks next to the Church of the Seven Martyrs) and was also told it was a good spot for swimming nude (by a local!) Sadly, that wasn't the case. It's beautiful, but there were groups of people, including families who had discovered the spot, so no chance. However, if you follow the path from Kastro's free parking just outside the village towards Paralia Panagia Poulati (Trail 1 on Google Maps), just before you get there, there is another small cove you can access and swim nude there. It's not an "official" beach and the path isn't as straightforward (you can get there after jumping over an old wooden fence and make your way down). It's worth it though, as no-one else will come!