I lived in Alaska as a kid, and my dad's boss was killed by one. They were out in a Zodiak glassing some mountains for goats, same scenario...seas were slick. His son turned around and saw it coming, had enough time to say, "Here comes a big one dad." It hit them, flipped to boat and that was that. Son and one other hunter pushed the Zodiak to shore and survived. He watched his dad go under and never come up. They had to swim several hundred yards to shore where they took shelter under their boat. Tide washed his dad's body up, but they were so cold they couldn't do anything about it, then tide took it out again. They were rescued, and the body eventually recovered. I'll never forget that story for as long as I live.