I had a dream the other night that I might use for something.
I was in a cave with several other people, all of us in hardhats with lights and coveralls (like spelunkers or miners), and in a tunnel at the bottom of the caverns we found a steel plate in the cave floor, extending under the rock as if there was something under the cave itself.
Out of nowhere we had a torch and cut through the steel panel, only to discover a massive cavity. We dropped down maybe two or more stories onto an identical steel plate, and when we looked around we saw that it disappeared into the darkness around us. We could hear water dripping in the distance.
We cut through the second plate and discovered a room with a concrete floor and concrete walls, a bulkhead door, rusted pipes and ducts running across the ceiling and through the walls.
We explored the place, but much of it was the same; rusted steel and stained concrete, general decay, all lit by a weird yellowish light that seemed to come from the walls themselves.
We started to hear noises too, other than the hissing, gurgling, and banging pipes, and the sounds of some strange machinery hidden out of sight, we started to notice a low grinding, rumbling sound from somewhere deep inside the place, whispering, and strange animal noises from open shafts that led to the lower levels.
There was a really strong feeling that something bad was going to happen, and that we had to leave. But we couldn't find the way out, we hadn't left a lifeline to lead us back to the entrance.
I've been doing some work inside a barge lately; it's nearly pitch black, damp, claustrophobic, awkward to get around in, the inside is all ribbed steel and bracing, bolted hatches in the bulkheads. I have to wear rubber overalls, jacket, boots, and gloves, a breathing mask and a headlamp.
For once I have a damned good idea how this dream was inspired.