Tourism has become increasingly popular over the last century as more and more people have gained access to car travel, air travel and vacation time from work. One draw for tourists is the world's natural wonders, which are appealing for their scenery and wild, unspoiled beauty. Do you see a paradox for these areas? They must balance visitation and development with environmental preservation. Man-made tourist destinations -- iconic structures of immense cultural or architectural importance -- face similar challenges. The volume of visitors must be controlled because ancient walls and sculptures are often extraordinarily fragile and particularly prone to vandalism.
If left to their own devices, tourists can often be very destructive. Yellowstone National Park is perhaps the best example of such unfortunate behavior. Problems began soon after President Ulysses S. Grant created the park in 1872. Companies cut timber, killed wildlife, farmed the land and even rechanneled some of the hot springs. Tourists carved their names into rocks and trees, broke off pieces of ancient formations for souvenirs, and even put laundry soap in the geysers with the mistaken belief that it would hasten the eruption. In an effort restore order, the United States Army troops, under General Philip Sheridan, occupied the park in 1886 and stayed for three decades. Today, the park operates under a very strict set of rules as it continues to recover from decades of uncontrolled tourism.
Another natural place that has experienced environmental degradation is Mount Everest, though it's less due to ignorance than the sheer difficulty of trash disposal on the world's highest peak. A 1963 National Geographic article dubbed Mount Everest "the highest junkyard on Earth" due to the mountain of discarded oxygen bottles, kerosene containers and climbing gear left on its slopes. After another five decades of climbing, the trash has gotten so bad that climbers plan expeditions specifically for trash collection. For example, in April 2010, concerned climbers began an expedition to remove 4,410 pounds (2,000 kilograms) of garbage from the "death-zone," the dangerous region above 26,250 feet (8,000 meters).
Man-made wonders have also fallen victim to overzealous tourism. One such structure is the Great Wall of China, an ancient series of fortifications 4,000 miles (6,400 kilometers) in length that are believed to be between 2,000 and 400 years old. This World Heritage Site fell victim to centuries of deterioration from natural erosion and dismantling by local citizens, but it's the estimated 13 million tourists that threaten the one-third of the wall that remains. Tourists have removed bricks and defaced surfaces, while developers created a Disneyland-like atmosphere around some of the wall's more popular sections.
Angkor Wat, a Hindu temple in Cambodia, experienced similar problems, and those in charge responded with around-the-clock security patrols to prevent vandalism and theft. Massive restoration efforts by organizations like the United Nations Educational, Scientific & Cultural Organization (UNESCO), Apsara (a Cambodian authority created by governmental decree in 1995), and the World Monuments Fund (WMF) saved the site -- which hosted 321,000 visitors in 2001 -- from certain deterioration. While efforts to protect such destinations have increased over the last decade, the threat posed by intensive tourism and overdevelopment is still very real.