Dark ambient is a musical genre that mixes the ephemeral instrumentality of ambient music with a core of anxious dread. While you may never listened to it deliberately if you've watched any horror movies in the past few decades you've almost certainly heard it. Dark ambient is typically composed of a slowly evolving audio hellscape in which long drones, ethereal synth, warped voice clips, the sound of wind, and other unidentifiable sounds gradually weave together to create the atmosphere of a nightmare. Now, I have the suspicion that you are thinking "What you just described seems markedly unpleasant" and you would be right. Kind of. Dark ambient covers the whole range of negative emotions from teeth gritting anxiety to uncomprehending dread to hollow melancholy. Ever been in a tent at night with rain poring so hard you're sure the structure won't last the night and the only thing to do is wait and hope because anything else will just see you colder and wetter with the sun rise just as far away. It's not a pleasant experience but some part of you looks back on it fondly as that time you learned what it is to be small. A ball of fleeting warmth barely secured against the blind fury of a freezing sky.
Dark Ambient captures the feeling of exploring an abandoned building, hiking away from the hot zone, or watching the UFO descend some miles off. As with most ambient music the lack of a clear tempo robs it of any sort of immediacy or urgency. Like I said above it's not pleasant but it has a sort of allure in that it can bring across the same feelings that we watch horror to feel without needing the blood, brutality, and fleeing. If that sounds like something you'd be interested in then I'd suggest the following: Sleep Creature Void by Iron Cthulhu Apocalypse, Songs for the Abandoned by Cryo Chamber, and if you want something more industrial New Risen Throne has a harsher sound.
IRON NODER XV: LAST SECOND BARE BONES IRON NODER FREAKOUT!