Mike Buchheit | Yellowstone Association | Lamar Valley | Triple Peak Fork Trail

Commercial outfitters within the parks go to some of the same places, but they usually charge more and they aren't in the habit of hiring PhDs. Sign on for a course with the Yellowstone Association, for example, and you might prowl Lamar Valley with a wolf expert tracking the Druid Peak pack. Led by a Yosemite Association guide, you might hike the little-used Triple Peak Fork Trail, enjoying vast alpine meadows, stunning peaks, and the solace of emptiness some 30 walking miles from the gridlocked Yosemite Valley floor. Take one of GCFI's 70-some courses - ranging from easy family and mule-assisted backpacking trips to rugged backcountry adventures requiring climbing, orienteering, and the ability to negotiate a narrow cliff ledge without bawling for help - and you might be lucky enough to hook up with Ken Walters, who, along with a master's degree in geology, sports a rabid interest in everything from religion to dinosaur gait.

"No one knows the Grand Canyon like our people do," says GCFI director Mike Buchheit.

But you'd be wrong to mistake field institute trips for simply an exercise in rote facts.

"The difference between rolling up to the rim, gaping for an hour, then heading off to Vegas and actually sinking below the rim is tremendous," says Buchheit. "Spending a couple of nights and just letting the canyon weave its magic leaves an amazing - and lasting - impression."