National Geographic Islander
Line: Lindblad Expeditions
Passengers: 48
Itineraries: Galápagos Islands
Winner of the 2002 Condé Nast Traveler Eco-tourism Award, Lindblad Expeditions was launched with a mission to simultaneously explore and preserve undeveloped destinations. Its partnership with the National Geographic Society confers access to NGS field sites and scientists. While Lindblad travels all over the globe, the Galápagos Islands have special appeal—both to nature lovers, who will find beauty and bio-diversity there, as Darwin did, and to Lindblad, which was one of the first two companies to offer cruises to the Galápagos back in the late 1960s. In recent years, environmentalists have raised concerns about the impact of tourism on the islands; Lindblad passengers can donate to the cruise line's nine-year-old Galápagos Conservation Fund, the entire proceeds of which fund local conservation projects. On this expedition ship, expect to rise by seven in preparation for a full day. The Islander is outfitted with kayaks, Zodiacs, snorkeling equipment, and wet suits so that passengers can explore any corner of the islands. Shore excursions take you close to tortoises, sea lions, and blue-footed boobies; all are fearless, since they've never been hunted by humans. Before dinner, meet with the ship's experts in the lounge for cocktails and an overview of the day. Says cruise specialist Richard Turen, of Churchill & Turen in Naperville, Illinois, "If you are comfortable getting into a Zodiac, going ashore, and walking on slippery rocks in the hopes of coming face-to-face with a giant sea turtle, Lindblad is the right choice" (800-397-3346; expeditions.com; ten-day Galápagos trip from $4,320).

Spirit of Endeavour
Line: Cruise West
Passengers: 102
Itineraries: Alaska, Pacific Northwest
It's only fitting that a company started by an Alaskan bush pilot and his Alaskan beauty-queen wife would offer some of that state's most adventurous—and yet comfortable—cruises. There is no shortage of cruise lines to choose from in the forty-ninth state, but Cruise West's smaller ships are able to get into shallow inlets and narrow fjords—so close that you can feel the ship rock when a glacier calves nearby. They also stop at more ports than all the other cruise lines combined, so there are plenty of itineraries to choose from. Since the Spirit of Endeavour is one of the company's fastest ships, it will maximize your time on shore. The Inside Passage voyage aptly combines breathtaking natural scenery, unusual wildlife sightings, the chance to walk through trails lined with carved totems in Sitka National Historical Park, and remote human communities. The route runs through several humpback whale summering spots; in fact, Cruise West is so confident you'll see a whale that they'll refund $250 of your fare if you don't. Other stops include Tongass National Forest, the Norwegian settlement of Petersburg, Glacier Bay National Park, and the Tsimshian reservation. If you're still thirsty for more of Alaska, Cruise West offers three pre- or post-voyage extensions: You can travel by floatplane to a wilderness lodge, hike through Denali National Park, or explore Prince William Sound in an even smaller vessel (888-851-8133; cruisewest.com; nine-day Alaska trip from $4,899).