In the booming global travel business, ecotourism is among the fastest-growing segments. Costa Rica and Belize have built national identities around their celebrated environmental allure, while parts of the world once all but inaccessible -- from Antarctica to the Galapagos Islands to Mount Everest -- are now featured in travel guides, just like Manhattan, Rome and other less exotic destinations. Advocates see ecotourism as a powerful yet environmentally benign tool for sustainable economic development in even the poorest nations. But as the trend expands, critics see threats to the very flora and fauna tourists flock to visit. Moreover, traditional subsistence cultures may be obliterated by the ecotourism onslaught, replaced by service jobs that pay native peoples poverty wages. Meanwhile, tour promoters are using the increasingly popular "green" label to lure visitors to places unable to withstand large numbers of tourists.

Rachel S. Cox is a freelance writer in Washington, D.C., who writes about health, design and environmental issues for The Washington Post and other publications. She previously served as associate editor of Historic Preservation magazine. She holds a B.A. in English from Harvard University and studied architectural history at the University of California, Los Angeles. Her las report for CQ Researcher explored the "Home Schooling Debate."