We wound our way up a rocky cliff-side trail toward Gunsight Pass, which straddles a ragged, 7,000-foot-high ridgeline in the heart of Glacier National Park. Forty mph winds buffeted us, and a severe case of "bearanoia" held us in its grip.

The rangers had suggested Gunsight Pass because it offered stunning views and a relatively low chance of a grizzly encounter. My fiancée and I nonetheless compulsively observed the rules for backpacking in grizzly country. We sang continuously as we hiked to avoid any surprise encounters. We vigilantly watched for bear signs. And, each night, we hung our aromatic "dining" clothes with our food, high above the ground and well away from our tent.

We had also armed ourselves with no fewer than three cans of "grizzly strength" pepper spray. This spray, derived from cayenne peppers, is twice the strength of what cops can legally use on humans. A ranger told us that he once saw the spray used on a charging grizzly, and that the bear looked as though it had run into a brick wall.

Before I headed to Montana, my imagination was fueled by vivid stories of grizzly encounters, giving me some sympathy for my fiancée's already strong fear of grizzlies. But my concern was mixed with an almost obsessive fascination and curiosity: I had backpacked several times in grizzly country, but had never seen a grizzly.

Sarah and I were now hiking above timberline, making our way around switchbacks, slowly climbing into the fierce headwind towards Gunsight Pass. Thick clouds formed a low ceiling just above the pass.

Then, upon rounding yet another switchback, I saw it: a behemoth of a grizzly about 75 yards up the trail from us. This bear was about twice the size of the stuffed grizzly sow displayed at the lodge we'd stayed at a few nights earlier.

"OK, let's turn around and slowly head back down," I said, thinking we'd gain more distance and then, perhaps, watch the bear for a while. As we retraced our steps, Sarah walked directly in front of me. She had not yet seen the bear and did not know how close we were to it. She announced, in a falsely calm tone, "I'm getting my pepper spray ready."

Sarah stopped to un-holster one of her two cans of pepper spray. I looked back to see that the bear was now looking at us. Sarah held the can in front of her and fiddled with the trigger guard. Then, with a deep ffffffffffttt, a cohesive yellow cloud swelled from the nozzle, sitting motionless for a split second before a gust of wind carried it over Sarah's shoulder and directly into my face.

Excruciating pain hit me; I was blinded. It felt as if razor blades were slicing into my eyes and my face had been set on fire. I was beside myself, yelling in agony. And I had no idea what the bear was doing, or what would happen now if it approached us or became aggressive.

Hardly able to speak, I urged Sarah to help me get around another bend in the trail. I wanted desperately to get out of the bear's line of sight. Sarah -- worried that the spray might permanently blind me -- was now distracted from her utter terror of the grizzly. The bear, Sarah reported, had not moved. He was no longer even looking at us. In fact, he had simply returned to eating whatever it was that he was eating.

We struggled down the trail another 20 yards or so. Once out of sight of the bear, we frantically poured all of our drinking water into my eyes and face. The water soothed the intense pain, but only temporarily. I still had difficulty breathing, and I doubled over with convulsions as my body tried unsuccessfully to expel the oily pepper residue.

Sarah watched my pain-crazed behavior in horror. Yet she remained remarkably calm. She began a loud monologue intended to ward off bears, describing how nice it would be to get home, what kind of dinner we would eat that night, and so on. We resumed our descent, ultimately trudging more than eight miles, and reached the trailhead just before dark. We never saw the bear again.

We drove to the lodge that was home to the stuffed grizzly bear. After calling the emergency number on the side of the can, I took a long shower. Eventually, we made our way to the lodge's fireplace, where I relaxed with a much-needed whiskey. Nearly six hours had passed, and the pain had mostly faded. As I set my drink on a table decorated with wrought-iron grizzlies, and stretched my legs on a carpet patterned with grizzly silhouettes, I realized that despite my ursine obsession, the most dangerous creatures prowling bear country don't have four legs. They have two.