St. Croix's northern hills, however, give way in the south to a plain that varies from rolling to level. The lofty hills and deep valleys of Virgin Islands National Park cover nearly two thirds of St. John. Native tropical forests are found only on St. Thomas. Only 5 percent of the land is forested, though the government has replanted parts of St. Croix and St. Thomas. All of the islands are surrounded by coral reefs.
Tourism is a leading industry.
Visitors like the tropical climate, beautiful scenery, beaches, and sport fishing. Proximity to the United States mainland and free-port status also attract tourists. In addition to the traditional rum-distilling industry, chemicals, pharmaceuticals, and clothing are manufactured on a small scale, and watches are assembled. In the 1980s the petroleum-refining and alumina industries on St. Croix were expanded. Exports are shipped mainly to the United States, Puerto Rico, and the British Virgin Islands.