Thinking about a new place for a cruise, a charter or just a vacation? Take a look at some of these islands, which Coastal Living calls the “best secret islands on earth,” with white-sand beaches, fresh seafood and, best of all, no crowds. Skopelos, in Greece (pictured above), caught my eye, with its hidden coves, blue-roofed tavernas, Byzantine churches and endless views of the turquoise Aegean. It also has the beach that Hollywood used for scenes in Mama Mia. In Belize, Caye Caulker is a laid-back, five-mile-long strip of land where you can snorkel among the nurse sharks and rays at…