St. Croix, the largest of the U.S. Virgin Islands, is best known for its unique blend of Danish colonial history and world-class underwater scenery. It is home to the Buck Island Reef National Monument, which features one of the only underwater snorkeling trails in the U.S. National Park system. Historically, the island is famous for its "Seven Flags" heritage, having been ruled by several European powers, most visibly the Danes, whose influence is still seen in the pastel-colored architecture of Christiansted and Frederiksted. St. Croix is also the headquarters of the world-famous Cruzan Rum and Captain Morgan distilleries, offering popular tours and tastings. Unlike the busier St. Thomas, St. Croix is known for its more laid-back, local vibe and diverse geography, ranging from lush rainforests on the west end to the arid, desert-like terrain of Point Udall—the easternmost point of the United States by longitude.