Sustainable Kenya
Join Brian Mullis, co-founder and president of the nonprofit Sustainable Travel International, for this classic safari with a focus on tourism models that work. Stay at the Maasai-owned Campi Ya Kanzi, where your dollars help preserve the land for wildlife and the nomadic lifestyle of the Maasai, and the safari camp at Lewa Downs Conservancy, home to 11 percent of Kenya's black rhinos and a community development program that brings economic viability to the surrounding villages through initiatives such as micro- financing. Big Five Tours & Expeditions: "Carbon-Neutral Kenya Safari," 12 days; $8,550.

Rustic China
Cut off from the rest of the country by rugged mountains, the southern provinces of Guangxi and Guizhou are largely unspoiled—tranquil lakes, jagged karst peaks. The region is home to many minority groups, many of whom still wear traditional dress and work at cormorant fishing and papermaking. You'll stay in a series of rural homes. The Beijing-based operator works with villages to ensure that tourism doesn't harm the community. One Guizhou village, for instance, closes itself to travelers three months each year to help maintain their traditional routines. Wild China: "Old Country Living: Wandering the Rustic Landscapes of Guangxi and Guizhou, China," 12 days; $2,800.

Polynesian Voyage
From the mysterious moai of Easter Island to Tahiti's bustling capital of Papeete, this voyage aboard the 110-passenger Clipper Odyssey takes you to some of the most far-flung spots on Earth. Included are the Marquesas, with vertical peaks that disappear into the clouds and coral-encrusted rock walls made for scuba diving, and the largely inaccessible Pitcairns, where you'll encounter descendants of the famously mutinous crew of the Bounty. Along for the ride are several experts, including Jack Grove, Zegrahm co-founder and a leading authority on the fish and marine environments of the eastern tropical Pacific. Zegrahm Expeditions: "Beyond Rapa Nui: Easter Island, Pitcairns, Tuamotus, Marquesas, Tahiti," 20 days; from $12,880.

Here Come the Raptors
Every fall, millions of raptors from North America funnel through Veracruz, Mexico, on their migration south. Dave Mehlman, director of the Migratory Birds Program at the Nature Conservancy, and local birding guides accompany you. You'll also see archaeological ruins, shade coffee plantations, and more than 100,000 raptors and vultures fly overhead on most days. Nature Conservancy: "Veracruz River of Raptors, Mexico," 9 days; (Sept. 25-Oct. 3) $2,450.

Arctic Canada
Jutting north from Canada's heartland into the Arctic Ocean is the immense Nunavut Territory, rich in Inuit culture and teeming with wildlife: Arctic wolves, caribou, and musk ox. Explore this vast landscape from your base at Elu Inlet Lodge, co-owned by a local Inuit couple who accompany outings to interpret the land and wildlife. Frontiers North Adventures: "Elu Inlet Lodge—Unexplored Wilderness, Canada," 8 days; $4,640 (includes airfare from Cambridge Bay, Nunavut).

Insider's Silk Road
This journey from Istanbul to Tehran is full of authentic experiences, such as dining in a yurt in Eastern Turkey with Kurdish nomads and in the family home of your Iranian guide. Soon to be carbon-neutral, the Aussie-based outfitter opts for public transport when possible, such as the bus ride from Safranbolu to Amasya, Turkey. Intrepid Travel: "Istanbul to Tehran," 18 days; $2,220.

Alaska and Russia, Neighbors
Set sail from Nome, Alaska, on the small expedition ship Marina Svetaeva for the seldom-visited Wrangel Island, pack-ice permitting. On its way, your ship will ply the Bering Strait, the 62-mile-wide waterway that separates Alaska and Russia, and call on the Chukotka Peninsula, home to indigenous people who still live a traditional life of reindeer herding and hunting. Aurora Expeditions: "Arctic Ocean Discoverer, Bering Strait and Wrangel Island," 13 days; $5,490.