9. Safari in Tanzania

The trip: Yes, there is something a little unsettling about coming thisclose to a lion or cheetah in the bush, especially when you're actually sharing those same bushes with them—on the ground rather than inside a Land Rover. But a few hours from now, the butterflies in your stomach will be settled by a gin and tonic timed to the Tanzanian sunset. Any stay in an exclusive wilderness camp in the Tarangire National Park is pretty extraordinary, but what makes this safari so special is that forays into the Serengeti are conducted both on foot and by vehicle. You'll meet some of Tanzania's 120 tribes. And you'll see lumbering bull elephants, graceful giraffes, and, if you're there between January and March, some 2 million wildebeest migrating across the plains. (You might want to move out of the way for this last phenomenon.)

Why go? There's nothing new or gimmicky about this classic safari, which is precisely the point: It's about witnessing nature at its most feral, untouched by time or civilization.

What to pack: The beefiest memory card your camera will take.

Your guides: Mark Thornton, who personally takes only 100 guests on safari each year and who has exclusive access to some of Tanzania's most wildlife-rich areas.

Difficulty: 2 out of 10. If you can walk—with the knowledge that you might need to run—and press a shutter, you can do this trip.

Thornton Safaris
Tel: 011 256 78 754 1686
12-day safari, including lodging, meals, and guide service, around $7,000 per person

10. Dive the Great Barrier Reef

The trip: Let's face it, few of us will actually get to explore outer space, despite the best efforts of Sir Richard Branson. But we can come pretty darn close by donning a mask, an oxygen tank, and a pair of flippers to float through some of the 2,800 coral reefs that make up Australia's Great Barrier Reef. Drifting through the water really is akin to spacewalking, and the creatures—you'll be lucky to identify even a third of them—are decidedly otherworldly. Choose a private, low-impact area such as Wilson Island as your base camp. A coral cay that's actually part of the reef, it contains a mere six tents housing only 12 guests at a time. Since you're the only guests, beaches are deserted, and you can snorkel first thing in the morning. It's also located in-between the two prime dive sites of Lizard and Heron islands, with 1,500 species of fish and loggerhead turtles. After toweling off, you'll sip an Australian chardonnay, dine on local ingredients, and slumber in king-size beds. Which is a lot more appealing than strapping yourself into a spaceship.

Why go? The world's coral reefs are swiftly disappearing. But the eco-oriented Wilson Island allows you to both see the threatened treasures and help preserve them for your grandchildren.

What to pack: Wrinkle-free clothes. There are no irons on Wilson Island. No electricity either, for that matter.

Difficulty: 3 out of 10. No diving experience is necessary.

Your guides: Voyages Hotels & Resorts, the group that owns Wilson Island. They're best known for helping to protect, through sustainable tourism, another Australian treasure: Ayers Rock.

Wilson Island
Tel: 011 61 2 8296-8010
Four-night package, including lodging in a luxury tent, meals, drinks, and snorkeling gear, $1,620 per person; $263 additional for four days of diving (three dives per day) from nearby Heron Island

11. Sail in Antarctica

The trip: For anyone who grouses that adventure travel has become too soft, meet the Seal. The 56-foot-long aluminum cutter has no plasma TVs, no marble tubs, no Bose surround-sound speaker system. Instead, the six-passenger Seal is specially fitted for the Antarctic, with a swing-up keel to handle groundings and with watertight, well, everything. During this month-long trip through Antarctica, guests can focus on peeping at penguin colonies, iceberg-clogged coves, and frozen islands. Imagine the constant groan and splash of glaciers and the feel of the southernmost earth beneath your feet as you disembark to explore dormant volcanoes. The sail starts and ends in Puerto Williams, Chile, with a good measure of true adventure, such as when passengers harness themselves to the deck to take on Cape Horn and the Drake Passage. Nearly 24-hour daylight can make sleeping a distant thought, but the wine-stocked galley, hot showers, and private cabins add just enough softness to really enjoy the adventure.

Why go? It's the most impressive—and most genuine—way to visit Antarctica.

What to pack: A permit for any research you'd like to conduct on the seventh continent: This is a real expedition, with fellow crew members likely to be taking notes on marine biology, geology, and more.

Difficulty: 6.8 out of 10. There may be vino on board, but this is no booze cruise. Sailors should be prepared to handle frigid, treacherous conditions and to help out with daily boat work.

Your guides: Kate and Hamish Laird, sailors as tough as their boat. They've been exploring Antarctica for more than 20 years and have logged 26,000 safe miles on the Seal.

Seal
Tel: 603 868 5850
28-day charter, including food, wine, and safety equipment, $52,500 for up to four people

12. Climb Half Dome

The trip: With apologies to Ansel Adams, even the sharpest of photographs fails to capture the American icon of Half Dome, the granite monolith rising nearly 4,800 feet from the valley floor in California's Yosemite National Park. To understand a bit more about geology and the United States—and yourself—stop gaping and start climbing. The good news: You don't need technical rock-climbing skills or gear like you would for, say, El Capitan. You do need to be prepared for encountering as many as 1,000 fellow hikers on a summer weekend. Go early in the morning and plan for about a ten-hour round-trip hike. The series of trails on the backside leading to the summit pass through woods and waterfalls before climbing up rocky switchbacks to the final, 45-degree section, whose steepness is made manageable by a series of cables. The sheer rock wall is just scary enough to leave you feeling even more euphoric as you stare down at Yosemite from the summit.

Slide show   Rock your world Over the eons, glaciers have carved and polished High Sierras granite into sheer-walled valleys of dizzying beauty around Yosemite National Park. more photos

Why go? There's no better way to deeply appreciate the 1,200 square miles of Yosemite National Park.

What to pack: Gardening gloves, to wear while grabbing onto the cables for dear life.

Difficulty: 7 out of 10. Hikers should be ready to handle 17 miles and altitudes of 8,000-plus feet.

Your guides: Yourself, a hiking partner, and a map from the National Park Service.

Yosemite National Park
Tel: 209 372 0200

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