Royal Playa is the place to go if you love to dive and don't require night life.
It is located in Port Royal, toward the East end of the island away from the crowds. There are no roads. A 15 minute boat ride gets you there.
The diving is spectacular and close. Anything longer than a 15 minute boat ride is rare. No crowds, no cattle boats. Hardly ever see any other divers.
The accomidations are thatch roof cabanas. There is no power unless the generator is on and usually it is off by 8 or so in the evening. Rustic but more than comfortable. There is satelite internet so you can stay in touch if you need to.
The food is a mix. Lucinda, the cook, makes a mix of island and more American cuisine for breakfast and lunch. Dinner often consists of fresh seafood. We only had lobster a couple of times :)
There are sand flies like every where else but skin so soft worked quite well for us.
Did i mention the diving? Spotted eagle rays, nurse sharks, eels. and an aquarium like array of fish are common. Wonderful variety of walls and gentle sandy bottoms. There are barrel sponges galore, some of them bigger than you. Some of the best any where in the world.