I recommend everyone watch the above classic from 1937. When you're diving with octopus' remember they are aliens and have ways to destroy you that you will not expect. This one is one of the one's that all diver's are warned about. Moral of the story is don't mess with big octopi, especially when they have knives.
Find comfort in chaos and the world is yours.
Side note: I've watched an octopus wave back to someone that waved at them, and for me if an animal communicates "hello" back, I will not eat said animal. Which is messed up because octopus are delicious, but off the menu.