When we close our eyes to sleep, we shut ourselves into a strange darkness. It’s not pitch black. There’s movement and shapes and the remnants of the light that is no longer there. It’s dim but not complete darkness. True darkness is rare and unpalatable. That kind of darkness is what permeates the Hadal zone. The deepest layer of the ocean, 6,000-meters down, and 5,000-meters from when the light ...