i was in alaska fly fishing and came within 10 ft of huge ass grizzlies on 3 occasions, never been more scared in my life.  the two scariest were:
1) fly fishing in a stream about 5 ft from shore, hear a noise behind me, look back, 10 ft grizzly standing up.  the guide yelled for me to cut my line and slowly back away and if it saw me and looked at me to stand up real tall and make as much noise as possible. it turns out that bear could really have given a shit we were there, just sort of followed us around looking for fish, but still, i almost shat myself.
2) all those pics of bears getting fish out of a waterfall are at the same place in alaska (like 90% of em), i think its called brooks falls.  well there is like an observation deck so you can watch like 10 or 15 bears (really cool), but to get to it you need to walk through all this grass and shit.  we walk through making a ton of noise, once we get to the deck we look back, and there is a 12 foot grizzly with THREE FUCKING CUBS literally 5 ft to the left of where we walked.  a slightly different route, or a little less noise, and we would have been FUCKED