That actually happened to me once fishing off some log booms near Gabriola island. I was about 13 and I got a monster fish on that bent my very stiff oldschool short boat rod in half and pulled me into the water. I managed to grab the rod as it was shooting down into the water but the fish came off. To this day I still wonder what kind of fish it was. My guess is a seal or a one of the monster 10' lings a diver told us he saw but not in the exact location we were fishing and catching small rock cod left and right. Too bad nobody had a camera.