One evening while high up in the Beartooth Mountains of Montana, a lady friend and I went looking for moose and elk. There was a high pitched bark rather far off and I thought it must be a hunters dog. It did not sound much like a bear to me at the time. We sat on a hillside overlooking a pond and waited. Then, from only a matter of yards away came a deep, loud "WOOF!" I knew in an instant that we were in a very unstable situation...with a grizzly bear. We stood up and I said to my companion, "We gotta get out of here...now!" She wanted to run and I said, "Don't you dare!" I walked backwards down the hill while she stayed behind me. I had pepperspray in one hand and a knife in the other. I felt like I should be wearing a sign that says, "Free Bear Food Here!" I really thought we were likely to be mauled and wondered how bad it might get. For twenty minutes he followed us down a hillside, through a meadow, and then circled our camp. Squirrels chattered away in the trees and he kept barking the entire time. We found out many months later that he was a Yellowstone transplant. This young male grizzly got into more trouble and eventually was destroyed. Rather a sad ending I think.  
One day while on safari in Zimbabwe, a few of us were tracking an old one-tusker bull elephant on foot. Just as I said to the guide, "Aren't we getting a little far from the hill?", He said, "Oh @#$%!" Without warning the elephant had turned on us and was now charging. As we all ran through the bush, I was thinking how neat it was to be running from an elephant in Africa. That is until the great beast let loose an earth shaking trumpet blast. At that moment I felt the warm rush of adrenaline coursing through my body. I concentrated on relaxing and running as fast as I could. The way I cleared fallen trees & scrub would have made Carl Lewis proud. After the elephant veered off, the guide looked up at me on the hillside above him and asked,"How the heck did you get up the hill so fast?" I answered,"I didn't want to get stomped by an elephant!"