Scraggly peaks and 620 miles of rugged coast draw Euro-masochists for canyoneering, sea kayaking, diving, climbing, mountain biking, and sailing, plus paragliding off 8,877-foot Monte Cintu and rafting the Class IV Golo River. But the sportif notch to carve on your belt is trekking the grueling Fra I Monti, or GR20 Trail, a 104-mile grind along the island's spine. Call France-based Corse Aventure (011-33-495-259119; www.corse-aventure.com).
St. John, USVI
Virgin Islands National Park, which claims about three-fifths of this emerald isle, is crisscrossed with 20 miles of jungle trails for hiking and biking and blessed with pristine coral reefs for some of the best snorkeling and diving in the Caribbean. Arawak Expeditions gets you out in the park on weeklong trips (800-238-8687; www.arawakexp.com). But schedule a few extra days to enjoy lounging like a Rockefeller.
Mount Waialeale, near the island's center, which gets more than 480 inches of rain a year, is a verdant backdrop for horseback riders, mountain bikers, hikers, and windsurfers. Kauai's trophy trek, the 11-mile Kalalau Trail, leads you from the cliffs of the Na Pali Coast, past 300-foot Hanakapiai Falls, deep into the spectacular Kalalau Valley. For camping permits, contact the Hawaii Division of State Parks, 808-274-3444.
Hike 10,417-foot Pico Duarte, raft Class IIIV Yaque del Norte, mountain bike in the Dominican Alps, windsurf off Cabarete, and surf the ten-foot waves near Sousa. Go green and stay at Rancho Baiguate, an eco-resort in the highlands (809-574-4940; www.ranchobaiguate.com.do).