The toll you pay to enter this Eden is sweat, pain and fear.(Gates of the Arctic National Park and Preserve, Alaska)

The route climbed to a high divide that was notched like a gunsight between bald granite cliffs. Humping a big load up the pass, I was preoccupied with the weight biting into my shoulders and the rocks shifting underfoot, so I didn't see the bear until it was less than 75 yards away. I paused to catch my breath, glanced up, and there he was: a 350-pound grizzly, loping across the talus that spilled down from the notch. Because the wind was at his back, he hadn't yet noticed me; a single path led over the divide, and I was on it.

Since this was happening high in the Brooks Range, well north of the Arctic Circle, there were no trees for me to climb. I didn't have a gun. Running, I knew, might invite attack. Too scared to breathe, I tried to remain calm but felt my mouth go dry.

The bear kept coming. At 30 yards, catching my scent, he stopped abruptly and reared onto his hind legs. His shaggy blond fur rippled in the breeze. The grizzly sniffed the air, stared at me, sniffed some more. And then he dropped to all fours and bolted in the opposite direction, sprinting across a jumble of tank-trap boulders at a speed that defied belief.

The date was July 2, 1974. Two decades later the memory is still vivid. For a long time after the bear ran off, I sat on a rock and just listened to the pounding of my heart. It was an hour after midnight. Mosquitoes swarmed around my face. Far above the divide, a prow of jagged granite burned orange in the twilight, illuminated by a sun that never set. Ranks of nameless mountains marched into the distance as far as I could see.

Over the preceding weeks I'd become attuned to wolf song and the whistle of golden plovers, walked through a snorting tide of caribou and gorged on fat grayling pulled from crystalline streams. Now I'd stared into the eyes of Ursus arctos horribilis, only to discover that the star of my nightmares was even more discombobulated by the encounter than I was. I would see four more grizzlies before the month was out.

I'd climbed and fished in the emptiest reaches of the American West, but Alaska made the wilds of the lower 48 seem insipid and tame, a toothless simulacrum. In the Arctic, for the first time in my life I was surrounded by real wilderness. Even as a callow 20-year-old I understood that such an experience, in the late 20th century, was a rare and wondrous privilege.

Six years later Congress recognized the singularity of the Brooks Range and set aside 8.4 million acres of it as Gates of the Arctic National Park and Preserve. The size of Massachusetts and Connecticut combined, Gates of the Arctic is the second-largest unit in our national park system, yet few Americans have ever heard of it and fewer still have been there. It is visited by some two thousand people a year, compared with the more than nine million who visit Great Smoky Mountains National Park or the nearly four million who go to Yosemite.

This gaping disparity is largely a function of access. Yosemite lies four hours by automobile from San Francisco Bay and the region's six million residents; tourists can gawk at El Capitan and Yosemite Falls without ever stepping out of their cars. Although Gates of the Arctic has scenery that rivals Yosemite's, it's situated in remote northern Alaska. It's impossible to drive through because there are no roads. Within the park boundaries, moreover, there are no ranger stations, no motels, no snack bars, no souvenir shops, no maintained campgrounds, no facilities of any kind and no footpaths.

The fact that Gates …