THIS SUMMER approximately 6,000 students loaded down with packs and supplies tackled the outdoors in expeditions that ranged from a week to an entire semester. They were attracted by the school brochures that show students hanging from cliffs, spearing fish or gathering on a glacier. But they were also interested in the prospect that the great outdoors would lead them to a new sense of self.

Two of the most popular of these schools are Outward Bound and the National Outdoor Leadership School. "The biggest obstacle you'll overcome is yourself," states the OB wilderness school pamphlet. OB takes approximately 8,500 students on wilderness courses each year: 60 percent are male and 40 percent are female; 10 percent return for a second trip. In 1982, a large majority were under 29 years of age; 4 percent dropped out of the programs. The cost for the peak summer months this year was $1,070 for 21- to 23-day courses or $650 for 8 to 9 days.

The school employs 100 instructors full-time and a total of 800 seasonally. Salaries vary, but full-time instructors earn about $15,000 a year plus living expenses.

The lure of leadership skills is also part of the at- traction of NOLS. Peter Simer, NOLS president, stresses, "If an individual is interested in refining (leadership) qualities, then he or she should come to NOLS."

NOLS, founded in 1965, leads about 1,500 students (mean age: 22) each year; 30 percent return for a second course. One-third of the students are female, and 2 percent of the students drop out. The one-month courses cost about $1,200, and the semester course is $3,000.

NOLS employs 70 instructors full-time and 130 seasonally. A full-time instructor receives $225 per week.

But Dr. Eric Gebelien, a PhD in environmental studies at the Cascade General Hospital in Leavenworth, Wash., is not convinced that these schools have the guidance capacity that some believe. "You don't have to go out and scare the hell out of yourself to get some sense of well being . . . Wilderness programs have no real criteria or data as to whether the programs are beneficial or improve one's self-confidence. The perspective student simply fills out a very basic application, sends in the money and they are on their way."

But Lance Ollsen, a professor at Montana's College of Great Falls, has spent much of his career studying wilderness impact as a means of therapy. "It depends on the school," Ollsen says. "There are most definately programs simply designed for a good time. Others do offer a chance to test one's abilities and confidence. With some people they work, there is self-image improvement . . . It is an individual matter. I think NOLS' intention is to produce people who can lead in the wilderness . . . I think Outward Bound has a therapeutic intention."

But in all the shuffle to climb both physical and emotional mountaintops, Ollsen adds, "I question the impact on the environment in the name of therapy. The outdoors is getting too trampled on by people. The more wilderness schools, the more environmental impact. I think that there are real ethical implications here."