So, my novel in large part takes place in the New York underground, specifically the sewers. They are pitch-black and filled with horrible creatures. They are known to the two main characters as the infamous "Dark Tunnels", as they have never been out of their utopian underground society surrounded by a dystopian planet. How can i really send shivers up the readers spine? i want them to be mysterious, ominous, and horrific.
That's a very broad question that can really only be answered by yourself, unless you're going to plagiarize someone else's story-telling. My suggestion is to do some research on the current state of the NY sewers (which I believe is rather poor), judge how well they'd hold up to your apocalypse, and then write line after line of "mysterious, ominous, horrific" narration and see what you can come up with.
You should never let them been seen for starters; that way you let your readers do your work for you, and let them make their own nightmares. It would also bring the suspense level up. There is many options here so why don't you have a entire pot of coffee and have a great idea come to you.
^^ Yepp Yepp! I wouldnt reveail too much, leave them mysterious. Like Nutty said, make the reader do the work. but make up for the lack of description with somthing to fill the void. sounds great.... when are we going to see some of it for critque
Unknown and horrible creatures in a dark, wet, environment underground. Poor little humans used to an unchallenging environment. Personally I think you've already got the basis for sending considerable shivers up many spines already.
I'm agreeing with the rest of the posters. Do a little research, if you feel the need, and add to what you have. Other than that, it already sounds creepy.
Just from what you've described, I think your story sounds fascinating. I agree with the others that it's critical to NOT describe what's down there. Leave it ambiguous in terms of what they look like, but focus on clues involving the readers' senses...i.e. sounds they make in the distance, what kinds of markings do they leave in terms of scratches on the walls and residues, etc. Just enough to let readers know that they're dealing with something monstrous and unnatural, but not enough to spell out what it is.
Not everyone's cup of tea, but Steven King did something similar at the end of IT! Never really explaining it, allowing our imaginations to do the work for us. This was the main problem with the film adaptation, we saw the creature and it didn't have the same effect as conceiving our own horror.
