Clods of mud fly into the air--one lands right in the lap of Susan Barley who, along with her 12-year-old daughter, Simone, are riding in the back of a Toyota Tacoma 4x4 that's axle deep in Guatemalan jungle goo. Both mother and daughter are laughing. In a couple of hours, they'll be at a camp deep in the Yucatan jungle, experiencing a once-in-a-lifetime adventure.

Barley and her husband, Jim Greenfield, are successful Seattle attorneys. The family loves to travel and see new sights, many abroad. Typical of most travelers, nice resorts are their mainstay, with a swimming pool close at hand so their daughter and nine-year-old son, Evan, can lounge after a day of hiking, boating, and sightseeing.

But now they're venturing out. As their children get older, they're looking for bolder adventures and new ways of seeing the world around them. And, for a growing number of people like them, the eco-tourism bug has bitten.

Unlike the typical family vacation that centers on driving great American highways, eco-tourism involves travelers being transported by guides into the more remote areas of a region by whatever means are needed--bicycle, canoe, kayak, motorboat, or four-wheel-drive vehicle. It's adventurous and educational.

For at least 30 years, entrepreneurial 4x4 owners in such places as the Oregon Dunes, Moab, the High Sierras, Colorado Rockies, and California deserts have been taking out-of-towners into remote areas to see the local flora and fauna while learning about the history of the region. But it's only been in the last half-dozen years that eco-tourism has taken off around the world.