A small archipelago of mangrove cays just off the coast east of Guanica, reached by a short ferry ride from the Copamarina pier. The largest of them, Cayo Aurora, is universally known as Gilligan's Island — a name that has stuck despite having nothing to do with the place. The cays are protected as part of the Guanica Biosphere Reserve, and the water around them is shallow, warm, and exceptionally clear.
The main draw is the snorkelling in the channels that wind between the mangroves: starfish, parrotfish, conch, and occasional rays. Bring food, water, and shade; there is almost no infrastructure on the islands themselves. The ferry runs on weekends and holidays for a few dollars round-trip.