These idyllic sister islands, 2 miles (3 km) apart at their closest point, offer visitors a relatively authentic island experience. Both have luxuriant mountain rain forests; uncrowded beaches; historic ruins; towering, long-dormant volcanoes; charming if slightly dilapidated Georgian capitals in Basseterre (St. Kitts) and Charlestown (Nevis); intact cultural heritage; friendly if shy people; and restored 18th-century sugar plantation inns run by elegant, if sometimes eccentric, expatriate owners.

The islands' history follows the usual Caribbean route: Amerindian settlements, Columbus's voyages, fierce colonial battles between the British and French, a boom in sugar production second only to that of Barbados. St. Kitts became known as the mother colony of the West Indies: English settlers sailed from there to Antigua, Barbuda, Tortola, and Montserrat, and the French dispatched colonists to Martinique, Guadeloupe, St. Martin, and St. Barth.

St. Kitts and Nevis, in addition to Anguilla, achieved self-government as an associated state of Great Britain in 1967. Anguillians soon made their displeasure known, separating immediately, whereas St. Kitts and Nevis waited until 1983 to become an independent nation. The two islands, despite their superficial similarities, have taken increasingly different routes regarding tourism. Nevis received an economic boost from the Four Seasons, which helped establish it as an upscale destination. St. Kitts, however, had yet to define its identity at a time when most islands have found their tourism niche but is now making up for lost time and notoriety with several high-profile high-end projects, including Kittitian Hill and Christophe Harbour, with a Park Hyatt. A fierce sibling rivalry has ensued.

Though its comparative lack of development is a lure, the Kittitian government is casting its economic net in several directions. Golf, ecotourism, and scuba diving are being aggressively promoted. And the government hopes the number of available rooms will increase roughly 30% by 2017 to more than 2,000, according to the "build it and they will come" philosophy. But is St. Kitts ready to absorb all this? The island offers a surprisingly diverse vacation experience while retaining its essential Caribbean flavor. Divers have yet to discover all its underwater attractions, and nature lovers will be pleasantly surprised by the hiking. There's now every kind of accommodation, as well as gourmet dining, golf, and gaming.

Meanwhile, Nevis seems determined to stay even more unspoiled (there are still no traffic lights). Its natural attractions and activities certainly rival those of St. Kitts, from mountain biking and ecohiking to windsurfing and deep-sea fishing, though lying in a hammock and dining on romantic candlelit patios remain cherished pursuits. Pinney's Beach, despite occasional hurricane erosion, remains a classic Caribbean strand. Its historic heritage, from the Caribbean's first hotel to Alexander Hamilton's childhood home, is just as pronounced, including equally sybaritic plantation inns that seem torn from the pages of a romance novel.

Perhaps it's a warning sign that many guests call the catamaran trip to Nevis the high point of their stay on St. Kitts—and many Kittitians build retirement and second homes on Nevis. The sister islands' relationship remains outwardly cordial if slightly contentious. Nevis papers sometimes run blistering editorials advocating independence, though one plebiscite has already failed. St. Kitts and Nevis may separate someday, but for now their battles are confined to ad campaigns and political debates. Fortunately, well-heeled and barefoot travelers alike can still happily enjoy the many energetic and easygoing enticements of both blissful retreats.