Wouldn't be surprised. People who dig places like this'll use natural caves if they can. Less work to widen them out than to dig it out entirely, in my experience. Plus they like bein' secretive and shit.

[ She sloshes forward a little faster, perhaps eager to find some dry spot despite her state lack of care about the water. She pauses after a few moments of silence, blinks. ]

Oh, those're pretty. Like... little mushrooms growing on the walls and stuff. They've got a little glow to them.