Game: Grab yourself a seat, friend.

"An alarm will go off, obviously. The rat-king tasked me to set it there whenever it wore out to alert us of anything coming from the tunnel. Unless he is nearby enough to hear it, it shouldn't. However, it will alert the other nearby rats."

"It last about 8 or so hours but it should be dispelling quite shortly. You can always crawl under it just to be safe, it is set to detect anyone over four feet."

Nibbles shrugs "Ive never been down that way. Rat-king always said stay out, that it is dangerous, and if I enter I will die, so I never bothered."

You guys start making your way to the crossroads, going slowly past the torture room, doing your best to subdue your light sources. You hear a couple hisses and chain rattles but make your way past with no issues. You arrive at the cross roads shortly after, looking at the two paths you haven't been down yet. The trapped pathway to the north, and the stream going south.

You listen to the waterfall for a moment, the noise you hear is coming from down the southern tunnel, in the direction of the stream.
Listening more closely, you can hear it isn't a very loud water fall, leading you to believe that it is either, the current of the stream isn't enough to make it anything spectacular, the fall off is extremely deep or it's a good distance away.

You guys carefully enter the water, after the initial shock you eventually get used to the chilled water. The water depth varies from 1/2 to 2 ft, you find as long as you walk normally, the current is easy enough to deal with. You make your ways down and the stream starts flowing faster and the depths get deeper, averaging from 2 to 3 1/2 ft. The cavern floor beneath is overgrown with mossy sludge, you have to slow down to avoid falling. Off to the side a smaller, dry tunnel branches off from the main flooded tunnel. The skeletal remains of a humanoid can be spotted near the entrance.