The expansive, abyssal darkness of the deep sea mirrors the mystique and grandeur of outer space. Hauntingly bioluminescent creatures shine like nebulae, 'marine snow' full of fish feces glitters like space dust, and alien-ish glowing sharks prowl the depths. And just like spacecraft, telescopes, and rovers, underwater submersibles can transport us to the oceans' coldest, darkest depths, revealing the creatures that live there.