Tip your hat to James Cameron, who completed a dive to the deepest part of the ocean over the weekend.
Most of us would flip out diving a few metres down in a submarine. He dove seven miles down in what amounts to a steel bottle.
I've done solo dives (shhhhhhhhhh, don't tell anyone!) and I've done them in the darkest of night, and let me tell you, it's creepy. Really creepy. I have never felt this alone as on a moonless night in the depths of the ocean, and I dove without any light, except the lights of my video rig which I kept shut off most of the time in order to keep curious fish away. It's really close and eerie.
But those were to a depth that I could reach the surface easily and quickly if an emergency happened. It took hours to get this ship back up.