I would say short of shooting it in the eye, as another person suggested it would be impossible to kill a Blue Whale, with a M16. The blubber that keeps the whale buoyant and warm in the deep ocean is extremely thick (over a 12"). Even when shot with very large harpoons whales did not die. read more
Interesting question. A typical round from an M16 is unlikely to penetrate the thick blubber surrounding a blue whale, and even if it does is likely to have little energy remaining. read more
and they aren't very gentle, killer whales will drown a baby whale. large whales can break killer whale's bones with their massive tail. one bullet from a very powerful sniper rifle into the brains or heart would do the job. read more