They'd have to drop down quite a ways, which would most likely lead to injury or death unless they figure out a way around that. Once they're in, they still need to contend with the acid water. Let us know how they're going to get through all of this, and we can see if it'll work! Then we'll see what they find.

Had more time to noodle on this. If they are able to dig through the dirt and flesh, and safely get down into the cistern, it gets pretty weird down there! Time and space gets funky, colors get very weird, and those fleshy bugs get very violent. It will be very disconcerting and they'll need to contend with the bugs and the acid and the world getting super funky.