I have fished in IA, the Isle Royal NP, the Smokey Mountains NP, the Yellowstone NP and the Grand Tetons NP. I had encounter elk and many deers crossing the river at a short distance, snakes taking a sun bath on a branch a barely couple of feet away from my face, Grizzlies fishing down stream in the Becheler river, otters cleaning the pool of fish in front of my eyes (they are better fishermen than me...). Beavers coming back to the dam (while I was on top of the dam). I hook a 3-4ft alligator in FL and he cut me off at the eye of the hook. That was a hell of a fight. I had a 5wt rod and he took a leach. I sneak close to a fox in an Iowa stream. He was just taking a nap in the sun at the side of the stream.
What I love most is the birds that come close to you when you are fishing quietly...
M