What has you dog done that scared you the most?

I was thinking the other day, and Gracie, our beloved Great Dane mix once decided to try to drink from the pond near where my friend and I were chatting. But 2 feet away was the lip of a huge waterfall that landed on giant granite builders below - the pond was a mill pond built for a factory that used water power, but went out when the hurricane destroyed it in 1938. Gracie was on the leash when she fell in, and panicked, and my friend and I was so scared we weren't going to be able to get her up on the banking without her - or me - being swept over the waterfall! We managed it, but were shaking afterwards - and Gracie, who was terrified of water (including rain) even before that, was trembling too!

I drove past that spot the other day and remembered that.

What has your dog done that scared you?