Sadly, my biggest fear is of other people with malice in mind. I have not been afraid while caching except once when we encoundered some, uh, Pine Barrens residents who were intoxicated and sort of scary. I'd rather take my chances with snakes, wild cats and bears.
sigh - me too. Not bad when I go with others, but being a single woman alone in the woods makes me feel a bit vulnerable. Luckily, no bad experiences so far.