The unspoiled great outdoors is truly a sight to behold. And behold it you shall from four ships whose itineraries celebrate natural wonders

Kapitan Khlebnikov
Line: Quark Expeditions
Passengers: 108
Itineraries: Antarctic and Arctic
Quark has been at the forefront of polar tourism since 1991—it was the first to bring nonscientists to Emperor penguin rookeries, the first to circumnavigate Antarctica, the first to transit the Northeast Passage. Although the more-luxurious vessels in the fleet make for a softer adventure, the ultimate way to see the poles is on an icebreaker like the Kapitan Khlebnikov. Just bring plenty of Dramamine: "These ships are rock-and-rollers," says cruise agent Paul Niskanen of Cruise Masters in Seattle. Your reward for the rough journey is entry to regions that are otherwise inaccessible. And when the ship can't go any farther, the onboard helicopters and Zodiacs can. Though originally designed for use in northern Siberia as a merchant marine vessel that also kept the shipping lanes open, the Khlebnikov offers comforts such as a heated indoor swimming pool and a sauna, as well as a staff-to-passenger ratio of 1 to 1.5. Arctic itineraries may yield encounters with musk oxen, the rare Leptev walrus, and of course the currently endangered polar bears. Sometimes the ship can make it all the way to the Lincoln Sea, near the North Pole; sometimes the ice pack is simply too thick. The Kapitan Khlebnikov's southern journeys focus more on human history, with descendants of great Antarctic explorers aboard as guest lecturers to recount family lore. All voyages feature scientific experts who help fill the days at sea with lectures and presentations; some also include a photographer or a painter to help you capture the unique scenery (800-356-5699; quarkexpeditions.com; 18-day Arctic trip from $14,500).

Ms Hanseatic
Line: Hapag-Lloyd Cruises
Passengers: 184
Itineraries: Antarctic, Arctic, Asia, Europe, South Africa, South America, Transatlantic
Some cruisers like their adventure light—remote destinations supported by luxury digs onboard. The Hanseatic is the ship for them, matching five-star accommodations and amenities to its wildlife-rich itineraries, which extend to the corners of the earth. The 25-day "So Close to the Gods" trip includes snorkeling off the coast of the Solomon Islands, and visits to the primal jungles of Papua New Guinea and Komodo Island's famous 300-pound dragons—this is a section of the South Pacific far from the reach of other cruise ships. The three-week Terra Magica itinerary plies a different but equally remote section of the same ocean, from Japan to Alaska. Along the way, the Hanseatic makes several stops for exotic fauna: crested murrelets on the Japanese island of Rishiri To, Steller's sea eagles and brown bears on the Siberian Kamchatka Peninsula, and rare whiskered auklets in the Aleutian Islands. Depending on your expedition, the ship has parkas, bikes, snorkeling gear, fishing equipment, and microscopes available for use. Historians, biologists, and published authors will also be along to make sense of these strange environments; if you don't want to attend their lectures in the auditorium, you can watch them on TV in your room. Passengers in the Bridge Deck cabins have butlers at their beck and call, 24 hours a day, to bring you breakfast in bed, an afternoon nibble, or extra sunscreen. Be careful to book a bilingual itinerary, since several sailings cater only to German-speaking passengers, the main clientele of this line (877- 445-7447; hl-cruises.com; 21-day North Pacific trip from $15,980).