This beach is just another branch of the beautiful Caribbean island of Culebra. Though Flamenco is the most popular but it gets a bit crowded at some times. If you want complete peace and serenity, the Carlos Rosario is the best option. The water here is much softer and the beach is never crowded. It is rather empty even on weekends to make it easier for you. The beach is also ideal for snorkeling and the most remarkable part is the beautiful coral reef that covers almost the whole horse shoe shape of the bay.
Google Map: https://goo.gl/maps/xzbJh9inJ8qBKSu38