
That's really
not useless! Imagine the scene; you're being chased by a sperm whale.... Eeeewww! Er, aye, anyhow, it's catching up quickly and you're getting tired so how to escape a fate worse than Cameron Diaz' hair in
that film scene?
Simple! All you'd need to do would be to dive to a depth of 2.2
6KM and the whale would have to give up and go home.
Now suppose you didn't know about the depth to which that whale can dive, you might only go down a couple of KM and stop, thinking you're home and dry when CRUNCH! Whale eats you and you die, or possibly get hurt quite a lot and covered in whatever it is that sperm whales cover you with. Worse still, you might dive to 3KM and become too tired to swim back to the surface.
Well I'll remember that now.
