Hiking or riding a mountain bike in Canada, I don't think there's anything scarier than seeing a couple of cubs on one side of the path.... and mamma bear on the other side.
You are between her and her cubs... not a good place to be!
Although.... there was this one time when I was hiking peacefully in Quebec, and a big deer jumped over a bush to land... face to face with me. The horrible screeching noise it made inches from my face still haunts my dreams from time to time....
