abandoned
adit
candle
catacomb
cavern
channel
coal
collector
corridor
dark
deep
derelict
digger
dirt
dirty
drainage
draining
exploration
flood
flow
flowing
gallery
industrial
inside
interior
iron
lost
mine
mineral
mining
ore
passage
pollution
resources
rock
rusty
sewage
sewer
sewerage
stream
subterranean
tunnel
underground
underpass
urban
vaulted
waste
wastewater
water