Do-good, feel-good vacations: extend a needed hand while earning karma points and burning calories in beautiful, exotic locations

FYI Forest inhabitants include alligators, snakes, foxes and bears, but the ones you'll really want to watch out for are the biting insects, including ticks. Pack bug spray, unscented sunscreen, a tent, sleeping bag and a heavy-duty pair of work gloves and sturdy hiking boots.

Karma points I knew my work was improving a sensitive ecosystem for future generations to enjoy.

Details The Sierra Club offers some 90 service trips throughout the United States, Canada and Puerto Rico, maintaining trails, monitoring mostly endangered species and participating in archeological digs (from $255 for a week plus $25 introductory annual membership, includes meals and campsite fees; 415-977-5522, sierraclub.org/outings/national).--Dorothy Smiljanich

Project Eco-preservation on Hawaii's Big Island

Hawaii Volcanoes National Park was established in 1916 to preserve the Big Island of Hawaii's unique volcanic features, invaluable archaeological sites, and fragile native plant and animal life (90 percent of it found nowhere else on earth).

As a Hawaii resident, I am well aware of the state's ecological fragility; it's seen more extinctions than any of the other 49. So I eagerly signed up for Wilderness Volunteers' Volcanoes National Park eco-preservation trip.

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Who goes Our group of 12 volunteers (five men and seven women) ranged in age from 16-76.

Elbow grease The project is rated strenuous, but it's hard to complain when you're surrounded by more than 200,000 acres of lush forests, petroglyph fields, and lava flow from an active volcano. No one--not even those most used to outdoor work--turned down the propane-heated shower at Anihou, a remote ranch, where we camped in tents.

It was rise and shine for breakfast at 7 a.m., then a two-mile hike to a worksite to spend about six hours clearing invasive plants and removing old barbed-wire fencing from trails, or cleaning up remote black-sand beaches.

Provisions The menu featured simple, wholesome food: granola with fresh papaya slices for breakfast, sandwiches and trail mix or dried fruit for lunch, and pasta or fish tacos for dinner; everyone took turns pitching in for kitchen duty and cleanup. The Park Service provided all ground transportation, including pickup from Hilo International Airport, 30 miles away.

Downtime In the evenings, some members of our group headed to a lecture or slide show at the Volcanoes National Park Visitors Center, while others checked out the active lava flow near Chain of Craters Road or trod along the four-mile Kilauea lki loop, which curves through exotic rainforests filled with 20-foot tree ferns.

FYI Must-pack items include a large backpack (about 4,500 cubic inches) sleeping bag, tent, durable work gloves and waterproof hiking boots.

Karma points We traded our sweat for the satisfaction of helping preserve one of the world's most breathtaking and vulnerable environments.

Details Wilderness Volunteers, a nonprofit environmental group, assists public-land agencies, including the National Park and the U.S. Fish and Wildlife services, in the preservation of outdoor recreation areas in the United States (from $239, tax-deductible, for seven days, includes food, campsite fees and ground transportation; 928-556-0038, wilderness volunteers.org).--Kathryn Drury