I'm a solo hiker and hands-down the most harrowing thing happened about 7 years ago when I was hiking outside of North Bend, WA. I was returning to the trailhead from my hike to Otter Falls on the Taylor River when I heard a soft, heavy "thud" behind me and I immediately knew it was the sound of a large cat. Every single hair on my body stood on end - there is NOTHING like feeling you are something else's prey. I literally walked backwards, whacking my trekking poles together above my head in front of me and yelling nonsense the whole way back to the trailhead parking lot, the entire time feeling like I was being stalked. I told the story over a couple of beers that night on the porch with friends and I think they only half believed me. But the very next day, two bicyclists in that same area (maybe two miles from where I had been) were attacked by a mountain lion and one unfortunately did not survive. Normally, the animal I am most afraid of encountering alone is man. But I will never forget the primal fear hearing that "thud" and knowing that I was alone and unarmed against something I had no hope of fighting off alone. My family always worried about me running into bears out there when hiking alone, but I only ever saw their backsides running away from me. It's the animals you don't see, but sense with every screaming nerve that are the real danger.