Halfway across the creek, the nerve endings in my feet began to feel like they were on fire. Direct snowmelt from the whiteclad peaks of the Trinity Alps had swollen these frigid waters, which I needed to pass through in order to reach the trail to lofty Caribou Lake. The cold was excruciating, and even though the shock triggered a rush of adrenaline, I had to subdue the impulse to quicken my pace. As the water level rose above my knees and its force multiplied, it became harder to grip the stones with my stiffened toes and not lose my balance. One fall would have ended the backpacking trip before it had even begun.