When we started this annual roundup of the world's top guided tours three years ago, we sought to bring readers the most transformative, sustainable, and authentic experiences. To our delight, there's no shortage of companies that share our philosophy. Whether it's staring down a king penguin in Antarctica, sharing mole with a Oaxacan family, or watching your kids in a pickup soccer game in Sardinia, this is the sort of travel that will stick with you. We hope our 2008 picks get you inspired.

Albania
"Land of the Eagles: Albania"
Andante Travels

The Americas
"Along the Americas' Coasts"
Maris Freighter & Specialty Cruises

Antarctica
"Icebergs & Emperors-Mawson's Antarctica"
Aurora Expeditions

Australia
"Arnhem Land Marine Rescue Project"
World Expeditions
"Australian Dreamtime: Billabongs, Beaches & the Bush"
Ker & Downey

Bhutan
"Hidden Treasures of Bhutan"
Geographic Expeditions

Bulgaria
"Cultural Crossroads, Bulgaria"
Country Walkers

Cambodia
"Project Cambodia"
G.A.P Adventures and Globe Aware

Canada
"CapeRace Eco-Culture Experience"
CapeRace Cultural Adventures

"Royal Canadian Rockies Experience"
Royal Canadian Pacific

Caribbean
"Sailing the Southern Caribbean: An Epic Sojourn Aboard Sea Cloud II"
Lindblad Expeditions

China
"Immersion with the Tribes of the Aini and Wa; Beijing to Simao, Yunnan"
A Bridge to China

Ecuador
"Andes to Amazon, Ecuador"
BikeHike Adventures

"Volunteer Galápagos"
Myths and Mountains

Egypt
"Exclusively Yours Egypt"
African Travel Inc.

Georgia and Armenia
"Mountains & Monasteries, Georgia and Armenia"
MIR Corporation

Guyana
"Great Green Guyana"
Journeys International

India
"Family India"
Greaves Tours

"Heritage India"
Cox & Kings

Ireland
"Sea Kayaking Ireland, The Northwest Coast of County Donegal"
H2Outfitters

Italy
"Sardegna Multi-Sport Adventure, Italy"
Ciclismo Classico

Japan
"Food Lovers Japan"
Intrepid Travel

Kenya
"Tribes and Trails of Kenya"
Sierra Club Outings

Mauritania
"Mauritania: Sahara Desert Expedition: Journey into the Land of the Moors"
Wilderness Travel

Mexico
"Oaxaca Up Close: Living the Day of the Dead"
Culture Xplorers

"Sierra Spectacular by Private Railcar, Mexico"
Canyon Travel

Middle East
"Caravan Cities of the Ancient Near East"
Martin Randall Travel

Namibia
"Namibia Desert Rhino Expedition: A Trails Exploration"
Wilderness Safaris

Nepal
"Himalayan Tree Planting Trek"
Journeys International

New Zealand
"New Zealand Discovery"
Mountain Travel Sobek

North and South Korea
"Contrasting Koreas"
Snow Lion Expeditions

Norway
"Lofoten Multi-Adventure, Norway"
Crossing Latitudes

Palau
"Palau: Oceania Odyssey"
Boundless Journeys

Panama
"Coiba Island: The Hidden Dive Secret of the Decade, Panama"
Wild Planet Adventures

Patagonia
"Futaleufu Explorer"
Bio Bio Expeditions

Russia and Mongolia
"Russia and Mongolia Overland"
Dragoman Overland

Seychelles and South Africa
"Surf and Turf, Seychelles and South Africa"
Seacology

Tanzania
"Explorers Safari, Tanzania"
Thomson Safaris

Tanzania and Kenya
"Four Volcanoes: Mount Kenya, Kilimanjaro, Mount Meru, Ol Doinyo Lengai"
Adventures Within Reach

"The Family to Family Safari, Kenya and Tanzania"
Micato Safaris

Thailand
"Family Adventure, Thailand"
Absolute Travel

Tibet
"Tibet: Journey to the Highest Himalaya"
National Geographic Expeditions

Tunisia
"Tunisia's Sahara and Oasis Trail"
Cross Country International Equestrian Vacations

United States
"San Francisco to the Wine Country"
Wine Country Trekking

"Southwest Safari Camp: The Other Chaco Canyon"
Southwest Ed-ventures

"Superlative Idaho"
ROW Adventures

Uzbekistan and Kyrgyzstan
"The Chaktal River, Uzbekistan, and Kyrgyzstan"
Mountain Travel Sobek