Many years ago I saw a video of a guy walking along a lake somewhere in Canada and a black bear stalked him for about 20 minutes slowly getting closer and closer. One time he tripped over a log and the bear rushed him and almost landed on him before he could get up. Eventually the guy went into the lake and tried to swim to the other side but the bear walked around and met him. He swam back to the original side and was able to escape.
I tried finding the video on YouTube but was unsuccessful. It left a cold chill down my spine and I never go hiking in the woods without protection of some sort..
On our trip to AK and Canada last year our only aggressive encounter of the hundreds of sightings was in BC with a black bear and we had to use the bear spray to get him out of our campsite.