Rain forests and tundra, deserts and savannas, mountaintops and undersea reefs. No spot on the planet is too remote for the movement that has changed the face of leisure travel. Ecotourism, in all its various guises—green tourism, sustainable tourism, adventure travel—has gained traction as enthusiasts seek to experience the earth’s wonders while treading lightly on them.

Lately a new subset of this boom has emerged. “Voluntourism” ramps the ecological impulse up a notch, providing ways for vacationers to help save the world’s sustainable resources. The trend has been described as a kind of mini version of the Peace Corps. Depending on your interests, you could find yourself repairing trails leading to Old Faithful, tracking sharks in the Atlantic, or mixing cement for housing in the Andes. Voluntourism is becoming a significant growth sector of the travel industry. Online trip planner Travelocity, for example, now partners with tour operators such as GlobeAware, Cross-Cultural Solutions and Take Pride in America, which specialize in launching voluntourists on service-oriented vacations.

One organization, the Massachusetts-based Earthwatch Institute, places travelers in cutting-edge field research projects around the globe. During these stints, most lasting one to two weeks, volunteers work alongside professional, peer-reviewed scientists, all authorities in their disciplines and all expecting meticulous performance and dedication from their newfound assistants. This arrangement is probably the ne plus ultra of the voluntourist experience, and Earthwatch is the acknowledged arranger. Here are three expeditions that offer natural beauty, enjoyment and meaningful participation.

Slide Show: Exotic "Voluntourism" locales

Easter Island
Easter Island (Rapa Nui) is a lonely little triangle of mid-Pacific volcanic rock. Two thousand miles from either of its nearest populated neighbors, Tahiti and Chile, the island is generally regarded as the world’s most remote inhabited site. Despite the isolation, it was once home to a vibrant civilization that left behind, among other relics, the familiar Moai, the gigantic stone heads that have become the island’s signature icons. The resonance between Rapa Nui’s culture and its rocky, wind-whipped terrain have made it an important ongoing venue for scientific inquiry.

Archaeologist Christopher Stevenson, a longtime Earthwatch associate, oversees much of this scrutiny. Three times a year he musters teams of paying volunteers for 14-day tours as researchers to probe the mysteries of Easter Island. Much of the work is archaeological, but it’s not just a search for pottery shards or petroglyphs. Stevenson is fascinated with the decline of Easter Island’s civilization and the islanders’ failure to maintain sustainable agriculture. He focuses primarily on the fragile balance between farming in arid, inhospitable soil and the powerful infrastructure that plundered labor and resources to build temples and the monumental Moai. Easter Island is a “model planet Earth,” Stevenson says. It demonstrates the negative pressures that sociocultural demands—political power and religion included—can exert on the sustainability of a delicate ecosystem.

Stevenson’s volunteers extract and analyze soil from ancient gardens and small farms around the island. Directed by his fellow scientist Sonia Haoa, they also conduct plot surveys and collect artifacts at promising archaeological sites—data crucial to the ongoing study. The value to the volunteers themselves, aside from an extreme version of “getting away from the office,” is multifold. “They learn about being part of a research team,” Stevenson says. “They acquire important skills required for field investigation, including adapting quickly to a new culture. To a large degree, they’re learning what actual science is all about.”