Catch a boat from the dock just opposite the Cartagena city gate and take a ride out to the Islas del Rosario, a protected archipelago of 27 coral islands surrounded by reefs teeming with exquisite flora and fauna. Island activities include snorkeling, diving, fishing, or just sunbathing on marvelous white-sand beaches—whatever tickles your fancy. Some vacation homes and hotels were built on the islands before they were designated a national park, so there are small communities on some of the larger islands. Isla Rosario has a small aquarium and oceanarium, with dolphin shows and sharks. Make sure to try local seafood like pargo rojo with coconut rice and fried plantains.