Now, as Anying said this, indeed, they were facing a huge challenge.
If, really, it's down another 30 meters or even further, then, if their ropes can't reach, there's no way they can descend.
Once someone jumps down and falls to the bottom of the valley, climbing back up becomes an impossible task.
Moreover, how much further down does it actually go? No one can estimate that.
Once there's no way to come back up, in the morning, when the surrounding seawater starts to rise, the swamp will follow the tide in, by then, it could suffocate people alive in there.
So, no matter how you look at it, this plan of theirs to go down is actually quite a risky move.
"Forget it, now that we're already at this point, it's meaningless to discuss those, even if it's not enough, we can double-check to see if there's actually such an entrance."
"Alright then, at this point, we can only do that."
