I think that is a male fantasy, as most nude beaches are about nudity but I know there are some where more happens or isolated areas, having had sex on the beach it does not excite me as the sand is always in the way and nothing more discouraging than sand inside a woman and I would think likewise on a man tool but the concept or fantasy sounds delightful. Towels can help but sand gets in everything at least my experiences with sand and beaches. Everywhere and everything. Like razor stubble I do not enjoy it between my legs. If you know what I mean.