窟 - cavern

cave; cavern; grotto

cave; cavern

den of vice; rogue's den

cave diving

opium den

enchanted cave

brothel; house of ill repute; red-light district

den; haunt; hangout; nest; lair

slum

very shrewd in preparing a means of escape; being very good at escaping danger

cave bear (extinct, Ursus spelaeus)

treasure mine