Courtesy of Butterfiled & Robinson/ David McDougall
Kayak the Great Northern Peninsula's shores and hike the 1,000-year-old Viking settlement L'Anse aux Meadows. Along the way, you'll dine on wild caribou and native lobster. Butterfield & Robinson gives a percentage of its profits to local environmental organizations.
Trip Tip: Trek to the abandoned fishing villages of Ireland's Eye and Curley's Harbour, untouched since the '60s.
Luxury Level: You'll spend an evening at the secluded 1865 lighthouse overlooking Iceberg Alley, then three nights at the soon-to-be-wind-powered Fishers' Loft Inn (fishersloft.com).
Butterfield & Robinson; 866/551-9090; butterfield.com; $7,995 per person, all-inclusive; July 7-13 and 14-20.
Courtesy of Habitat for Humanity
As part of Habitat for Humanity's Gulf Coast Recovery Program, spend five days building houses for low-income families. The work ranges from gardening to building roofs.
Trip Tip: At night, head to lively Frenchman Street for the best jazz in the South.
Luxury Level: Those who forgo a hotel can check into Camp Hope, run by St. Bernard Parish. Heat, AC, laundry, showers, and three meals a day are provided, but volunteers sleep in bunk beds.
Habitat for Humanity; 504/861-2077; habitat-nola.org; $20 per night at Camp Hope; ongoing, year-round.
Arnd Bronkhorst / www.arnd.nl
Travelers on the 11-day trip to Abaco Island track bottlenose dolphins, beaked whales, and West Indian manatees. Your research helps to shape island conservation plans, and 100 percent of the trip fee goes back into Earthwatch-sponsored programs.
Trip Tip: Arrange a tour with Arkwild (242/367-4805; arkwild.org; from $50) to the 3,800-acre pine forest where the last eight Abaco Barbs—descendants of Spanish horses—still live.
Luxury Level: A three-bedroom beach house is shared with seven other people in Sandy Point, Abaco's main town.
Earthwatch; 800/776-0188; earthwatch.org; $2,549 per person, all-inclusive; 11-day trips depart January 8, February 26, and June 10 and 24.
Gerry Ellis / Getty Images
The Sierra Club organizes weeklong eco-immersion trips on the island of St. John. Amid the dense rain forests of the Virgin Islands National Park, volunteers assist archaeologists in restoring trails and 18th-century plantations, and attend lectures on eco-living.
Trip Tip: Bring your snorkeling gear to explore Trunk Bay, which has a 225-yard underwater route marked with plaques identifying the different fish species.
Luxury Level: Although the two-bedroom beach cabins are rustic, volunteers have a stretch of white sand practically to themselves.
Sierra Club; 415/977-5500; sierraclub.org; $1,175 per person, all-inclusive; February 9-16 and 16-23.
Courtesy of Greenvisions
Bosnia and Herzegovina
Hike the 6,400-foot Bjelašnica Mountain to visit three historic villages—Stanari, Dubocani, and Lukomir—that were temporarily abandoned during the Bosnian war. Locals show travelers how to cook Bosnian meals and weave traditional rugs.
Trip Tip: In Lukomir, trek through the 2,624-foot Rakitnica Canyon.
Luxury Level: You can choose to sleep in locals' houses or camp in tents.
Green Visions; 387/3371-7290; greenvisions.ba; five days from $500 per person; June through September.
Tour the country's capital, Yerevan, and see the Matenadaran archives, one of the world's richest collections of ancient manuscripts. Then travel by minibus to Gyumri, about 60 miles northwest, for language lessons and a stint documenting buildings damaged in the 1988 earthquake.
Trip Tip: Yerevan's Vernissage market (Republic Square) is an ideal place to pick up intricate handmade tablecloths.
Earthwatch; 800/776-0188; earthwatch.org; five-day trips from $3,400 per person, double, all-inclusive; July 2008.
Courtesy of Intrepid Travel
Tread softly through Europe by traveling via train. A veteran guide will map out local secrets, from St. Denis's market near Paris to the 377-year-old Eggenberg brewery in the Czech Republic's village of Ceský Krumlov.
Trip Tip: Donate to local charities through the Intrepid Foundation and it will match every dollar.
Luxury Level: Think apartments in Prague and home-stays in Bled, Slovenia.
Intrepid Travel; 866/847-8192; intrepidtravel.com; 34 days from $3,565 per person, all-inclusive except meals; Saturday departures year-round.
Get a dose of colonial culture in Antigua and teach children how to read at schools in the nearby villages of San Andrés Itzapa and Santa María de Jesús. Every morning, Global Vision staff picks up participants and shuttles them to these Mayan towns, where the company has helped more than 450 kids.
Trip Tip: Swing by Frida's (5 Avda. Norte 29; 502-9/782-0504; dinner for two $25), for taquitos and burros.
Luxury Level: Local families host volunteers in homes around Antigua; you're guaranteed a safe and comfortable stay, since Global Vision screens all host families.
Global Vision International; 888/653-6028; gviusa.com; from $2,070 per person, all-inclusive; month-long trips year-round, starting every Saturday.
Courtesy of G.A.P Adventures
Spend nine days migrating with native monarch butterflies—the best time to witness their flight is January. Head west to Parque Nacional Eduardo Ruiz in the city of Uruapan ("Eternal Spring") named for its lush vegetation—and venture to surrounding colonial villages, such as Angahuan, on low-impact foot trails. The highlight of the trip is the climb to El Rosario, a thriving butterfly sanctuary where millions of the delicate creatures inhabit a 10,000-foot-high protected forest. Great Adventure People (G.A.P), in partnership with the sanctuary, has planted hundreds of trees so that the butterflies can migrate safely.
Trip Tip: On your free day in Mexico City, ask your hotel to arrange a visit to the ancient pyramids at Teotihuacán, 30 miles northeast, and, en route, the Basilica of Guadalupe.
Luxury Level: Although the hotels are simple, most are family-run and located in colorful colonial houses from the 1800's.
G.A.P Adventures; 800/708-7761; gapadventures.com; $795 per person, meals not included; January 5-14 and 19-28, February 2-11 and 16-25, March 1-10.
Courtesy of Butterfield & Robinson/ Rob Howard
Skip the car and carbon emissions by biking through Vietnam. Cycle past banana plantations and villages, with stops at rice-paper craft shops and dragon-fruit farms.
Trip Tip: Bring home custom-made silk shirts from the celebrated
tailors of Hoi An.
Luxury Level: You'll wind down at five-star hotels, including the beach-side Evason Hideaway (sixsenses.com), in Nha Trang.
Butterfield & Robinson; 866/551-9090; butterfield.com; 11-day itineraries from $6,295 per person; various dates throughout the year.