ON THE 30TH DAY, MINDING the rain not at all, filing through the woods with a quiet authority, the students crossed the suspension bridge over Ruby Creek, rounded three switchbacks and caught a whiff of carbon monoxide.

"Oh my God, there it is," said Amy as a concrete span of the North Cascades Highway loomed into view.

"Swivelization!" said Ellen, with a new, ambivalent note in her voice.

On the final yards the file broke apart. "Fall in line," said Fred, the leader of the unsupervised "small group" expedition.

And there it was: the end, a gravel turnout past which cars hurtled at incredible speeds like 45 miles an hour.

"MELLY!" said Amy, as they were reunited with their instructors, who were waiting for them at the roadhead.

There was a round of hugs, a quick recap of the 22-mile trek Fred's group had made along Jackita Ridge and Devils Park.

By 6, when the NOLS bus arrived, the whole group was assembled. Their packs stowed, the students took seats beside the members of a NOLS mountaineering course who had been picked up some hours earlier.

There are two strains of people in NOLS: the reverent naturalist strain and the raucous mountaineer strain. The rowdy bunch already in the bus was clearly of the latter type, and the wilderness course students shrank in consternation as the peak-baggers bragged of their ascents, and boasted how they were going to go back to their motels in Mount Vernon and "rip the town apart."

In Marblemount, en route home, one of the mountaineers emerged from the Mercantile Grocery clutching steaks to his chest and crowing, "meat, meat, meat." Later that night as the two groups set up camp, Mr. Meat fetched up a two- inch black ground slug from the grass and kicked it into the air. It arced high and came down in the midst of those wimps in the wilderness course.

Reflecting on the spectacle of the slug-punting carnivores, Fred, who had often wished for more red-blooded interaction during the course, felt a sudden surge of affection for his companions, and the serenity of their camp.

Events rushed forward. "I feel the wilderness receding so fast," said Fred. They took hot showers, to live no longer like Dirty Bill Waters, the legendary character in the Methow Valley, who graduated from Princeton or Harvard, only to renounce swivelization after a bad love affair and live a life in which he never bathed or cut his hair, and drew his stove near enough to stoke his fire from the bed.

The expedition, which had been assembled at NOLS branch headquarters in Sedro Wooley, was dismantled there too. The students washed their pots, opened mail, bought a few NOLS T-shirts, settled their accounts, put on the rings and chains they had stowed in the safe a month before. They drove to a restaurant overlooking Samish Bay where the air smelled of cedar and sea. Blue herons flapped above the marsh. Dinner was seafood, memories, and separate checks.

Standing in the dusk, looking out at the San Juan Islands, Eric said, "It's funny when we were on the trip, all we could talk about was being outside. Now that we're outside, all we can talk about is the trip."

And the trip was what they talked about at their last camp, a party in Room 273 at the Town and Country Motor Inn in Mount Vernon. They had pizza before they said goodbye, not because they wanted it on top of dinner, but because they were back among the infinite possiblities of the world.