You fall for what seems like a long time... it's hard to breathe, and it's harder to see... the spots forming in your vision could be from any number of things... chemical induction into your system, brief flashes of chemically colored fungus on the walls, lack of oxygen to the brain... it's really hard to tell. eventually you splash into a 'lake' of some sort. you don't know how deep you go exactly, but you never do touch the bottom, and your lungs burn fearcly before you make it back to the surface. it's still black as pitch, and there's a general current pulling you in one particular dirrection, but it's much easyer than in the tunnel. (or at least feels that way)
you can hear the sound of the waterfall, and you can feel the dirrection the current is pulling you, but other than that, you have very little perseption ability.
-RuskiFace the GM