I'd recommend that you go to San Pedro, and island about 20 minutes flight from Belize City. It's very quiet, and only about a mile from the reef. Although there is a nice beach, you can't really swim in the water since it is inside the reef and full of weeds. But you can take quick boat trips out to the reef for fabulous snorkeing and diving.

If you want quiet, San Pedro is the perfect destination. And if you are lucky, you can get one of the world's rarest flights - a 20 minute commecial flight with a stopover!