The fourth level of the Mine structure has a flooded portion. It is understood to have had an influx of sharks and other dangerous beings.
Unfortunately in the fourth level down, to the very far right edge of the tracks is a cave of sorts. That cave, once entered will feel extremely different and discomforting to the person who enters. The space itself is not flooded, it appears to be something of a sandy beach with structures.
This area is ostensibly, a massive ancient trap. If you take more than four steps inside this cave - you will begin to feel the following sensations and possibly the after effects:
Piercing headaches
Dull and listless limbs
Sweats and fever
A strong urge to seek further
Night phobias or nightmares
Potential sleep walking
Anyone who has entered this cave should seek assistance from the Council and a Cleric immediately.
Under no circumstances are you to go further into the cave. Doing so will result in an untimely death.
Those found doing so intentionally, and having the luck to return may find themselves punished severely for their troubles and putting us all in danger from the brought illnesses.
Verity Voclain, On Behalf of the Council of 1050: Marehi Miller, Kalisa Inciya, Verity Voclain for The City of Threshold.
But if the earth ends in fire And the seas are frozen in time There'll be just one survivor The memories of our lifetime