"Just off mainland Puerto Rico is Cayo Icacos, a tiny, uninhabited island with a private, deserted-beach vibe — especially during the quiet season. A day spent on the island is the No. 4 activity in Puerto Rico, according to Tripadvisor travelers, who say the best way to experience the clear waters and white sandy beaches is by catamaran. The 5.5-hour snorkeling tour with East Island Excursions is complemented by the catamaran's underwater windows — perfect for viewing sea life from the ship — and onboard waterslide." - Travel + Leisure Editors