When wind and waves cooperate, it's only a swift boat ride from Casa de Campo's beach to Catalina Island.
Babtized 'Santa Catalina', by Christopher Columbus in 1494, the island is located about 2 kilometers from the mainland, and occupies less than 10 square kilometers. Part of the 'Parque Nacional del Este', it has some minor infrastructure, such as a bar (!!), postal box (?), art galleries, and of course, public toilets.
If you're in a 'Robinson Crusoe' frame of mind, you can walk 10mins to the end of the island and you'll be on your own (but also, of course, 10mins from the the nearest cocktail...). The beaches here are a dream, and so is the turquoise water.
I didn't dive here, but I was told that there are a number of good dive spots not far from the island, including a ship wreck. There is also a good snorkeling spot along the reef, near the arrival pier.
A warm thank you for my Dominican Republic experience — courtesy of Casa de Campo (http://casadecampo.com.do). @casadecampo