For most of the world's history, travel involved shorter trips within the home region. Even as technology allowed longer trips, most of the time these were travels for pleasure somewhere in the same country. But after World War I, airplanes and trains made it more appealing for those holidays to be taken in another country, even on another continent.

The amazing growth in vacation travel has had some negative impact on the world's resources and local cultures, primarily because an excursion to another region of the world often had the goal of exploiting resources. However, within the tourism field, the new trend of ecotourism is helping to minimize negative impact and is throwing optimism into the mix.

For decades, some of the most remote and beautiful places in the world have been hidden away completely or have been well-kept secrets. But global travel has literally put many of these places on the holiday map, with the resulting damage to unique environments and destruction of local traditions.

Fortunately, during the last couple of decades, there has been a noticeable shift of emphasis in tourism. More travelers are going on vacation trips that are environmentally friendly, with many destinations chosen because the traveler can actually help preserve or restore local resources. By some counts, tourism with a conservation focus now accounts for about 7 percent of international travel. This is expected to increase significantly in the next few years, to as much as 30 percent.

Combine ecotourism with other types of nature-oriented tourism and the total impact may be something close to 20 percent of all international travel. Most of the travelers who account for this astounding growth are between the ages of 35 and 54. Some believe this is a holdover from the Earth Day/Save The Environment philosophy this generation showed interest in a few years ago. But this age group also has significant financial resources that allow it to travel to distant places. This group is overwhelmingly college educated and they have the money to spend (more than the average tourist).

Statistics from early studies of ecotourism show that, in Kenya for example, a healthy lion can generate thousands of dollars in tourism revenue each year, while an elephant herd can account for tourism dollars in the hundreds of thousands. But, as ecotourism proponents emphasize, these natural resources must be preserved so that the economic benefit can be realized over the course of years. In fact, wildlife and biodiversity-focused tourism may actually rank among the world's top employers.

The potential of ecotourism, however, has not been tapped. In fact, the surface has hardly been scratched. In South Africa, for example, one developer plans to create a "paradise" of sorts, spending hundreds of millions of dollars to attract ecotourists. This site may include a floating casino, with generous amounts of healthy native animals in view. In Nepal, helicopter trips take travelers to altitudes where they can view the summits of higher mountains. This could reduce the number of climbers who destroy natural features while climbing.

With all of these possibilities, supporters of the ecotourism idea urge caution. As the industry grows, it will be necessary to make sure the correct steps are taken, so that resources are not overused. Early returns from ecotourism studies show that even this type of holiday travel can have negative impact on people and the environment.