In the 15th century, pirates including Francis Drake would lurk around Isla Catalina, waiting to pounce on Spanish ships sailing to and from Santo Domingo. Today this island ringed by fine coral reefs teeming with fish in shallow water is a popular destination for groups from nearby Casa de Campo; the resort has frequent shuttles making the 2km trip, as do large cruise ships.
Combine this traffic with a bar and restaurant and you won’t feel like you’ve found paradise lost. Most groups spend a couple of hours going snorkeling and having lunch, and divers head to a steep drop-off called The Wall. With enough people or cash it’s possible to charter a boat (most tour companies in the area, from Bayahibe to La Romana to Punta Cana and Bávaro, would probably be open to this for the right price) to an infrequently visited beach on the far side of the island. Isla Catalina is officially part of the protected Parque Nacional Cotubanamá.
