The fundamental challenge of travel is letting the world in while preserving what's uniquely local—from pristine ecosystems to indigenous cultures.

AdventureSmith Explorations
The Pioneer
What happens when a naturalist guide founds a cruise line? He goes carbon-neutral. Todd Smith started out leading kayak expeditions in Alaska. When he began running small-ship cruises, he brought the great outdoors to mainstream travelers—but at a cost to the environment. So last year his company, AdventureSmith, kicked off its Carbon-Free Cruising program, which offsets the carbon emitted by each trip through Sustainable Travel International's MyClimate program—at no extra cost to the traveler. AdventureSmith has donated $10,000 and expects to contribute twice that amount this year. Smith realizes that carbon offsetting isn't a long-term solution to the planet's energy crisis, though, so he's retrofitted one ship to run on biodiesel and has called on the entire industry to follow his lead (adventuresmithexplorations.com).

The Blue Yonder
Water Watchdog
This tour operator was created in 2003 specifically to fund the Nila Foundation, which is dedicated to preserving the Bharatapuzha River in Kerala, India.

Ritz-Carlton
Culture Lover
Hawaii's Ritz-Carlton, Kapalua, protects two sacred sites, holds story-telling sessions with local elders, and throws a yearly festival featuring traditional entertainment (ritzcarlton.com).

Tiamo Resorts
Sun King
Tiamo Resorts, on South Andros Island, in the Bahamas, is the first resort to run entirely on alternative energy—in this case, solar (tiamoresorts.com; see "Feel-Good Caribbean").