It's not the first time we've seen caves and spooky hollow places associated with the Dark Side in Star Wars. Caves are primal places that evoke many deep human fears: darkness, loneliness, being lost, coldness, confined spaces, and of course bats and other creepy living things.
So caves are a classic adventure site in many games. But so much so that they're kind of expected and players treat them as not particularly different to any other adventure site.
But it doesn't have to be that way. When a party ventures into a cave, you can make sure that the environment is unwelcoming, uncomfortable, and scary. Be strict on light sources and find reasons to take them away occasionally. Make characters have to squeeze through tight openings. Describe the cold, the damp, the silence. And of course whoever lives down here doesn't care about any of this and is at a distinct advantage.
Commentary by memnarch (who has not seen the movie)
Yeah, this is a bit of a letdown for a slimy pit so far. It looks a little foggy, which is good, but it's also lacking in anything slimy looking. Perhaps that's just due to the lighting though? I guess it would be hard to tell if there's not enough light to make something look slimy. However, and excepting the weird rock bit on the left, this shelf has to be pretty dry. I can't see a slimy shelf allowing for Rey to haul herself out this easily.
It is very amusing to see Pete try to get the Dark Side to come so Rey can be a part of Team Bad Guy. Pete just can't get a break when he's trying to play a bad guy character. I'm assuming it's really the opposite in the movie, and it's closer to the tree/cave scene from Episode V and Luke said to avoid the place. Or maybe Rey is looking for a challenge of some kind because Kylo successfully taunted her in the Force Phonecall. Either way, I'm looking forward to Pete failing to get the Dark Side to do anything he finds helpful in the future.
Rey: All right, fine. I surface and breathe.
GM: You’re in a grotto, dimly lit by a narrow cleft revealing the night outside.
Rey: Is there somewhere to climb out of the water?
GM: A rock shelf sits just above the water level.
Rey: I haul myself out.
Rey: So do I feel the shroud of the Dark Side falling on me?
GM: You’re damp and chilly.
Rey: I could do with a shroud then.
Rey: C’mon Dark Side! Show me what you got!
Rey: Wait. It rejected me earlier. I need to get its attention.
Rey: Jim just beat me to using PowerPoint in-character...
Rey: Any puppies in here that I can kick?