With the rumbling noises coming from the ballast tanks, the submarine surpassed the drooping realm of decay and continued its descent into an even more unknown and terrifying abyss.
From the City-State, tentacles hung down and that huge, pale eyeball completely vanished in the spotlight's beam; the vast, boundless dark waters refilled the view outside the porthole, with only occasional specks of light emerging from the depths (reflections from bubbles or plankton) to remind Duncan that he was inside a submarine navigating through water, not floating in the open, unsupported universe.
But he couldn't help forming strange associations—if seen from the perspective of "unknown and laden with horror," what difference was there, really, between the empty expanse of space and the dark, deep sea filled with billions of tons of water?