St. John, US Virgin Islands
Credit: Don Hebert / Getty Images

Virgin Islands National Park covers two-thirds of this island and includes some of the most unspoiled snorkeling spots in the Caribbean. Float around Saltpond Bay on St. John's far south tip and watch for sea turtles feeding on the seagrass, or follow the underwater snorkel trail in Trunk Bay on the north shore (great for beginners). To reach Reef Bay, you'll need a boat or hiking shoes, but the park service offers guided boat trips and hiking there takes you past pre-Columbian rock carvings. In this broad, shallow bay see stingray, Queen conchs the size of six-packs, sea fans, butterflyfish, angelfish, blue tang, fairy basslets, sergeant majors and even the occasional baby shark. Stay at Concordia Ecolodge, a short walk from Saltpond Bay and a quick drive to Reef Bay trails.