The clear blue Caribbean, beaches, coral reefs, marine life, and tropical scenery attract visitors to the main islands of St. Thomas, St. John, and St. Croix. In St. John, Virgin Islands National Park covers two-thirds of the island with tropical forests and hiking trails to explore its natural beauty. Resorts, nightlife, history, duty-free shopping, and passport-free arrivals (for U.S. travelers) make the U.S. Virgin Islands a popular vacation destination.