It must be known that Costa Rican culture does not really take a positive view of naturism. Indeed, you risk shock the locals if we see you. So there is no real naturist beach in Costa Rica. However, if I had to recommend places it would be:
- A beach at the edge of Manuel Antonio park where you can see naturists
- Montezuma which is a peace and love hippie village where you can see everything
However, be aware that if you really want to go naturism, Costa Rica is not the best destination for that.