The Water Monster or Kaernk: The Kaernk is a water-dwelling, other-worldly creature that is invisible to the naked eye.
Originating from the same world as Alexander of Brennenburg, this aquatic nightmare was delivered to the Baron from Johann Weyer as its saliva contained Tampter, an ingredient for a tonic to release Agrippa without killing him. Several water monsters were safely contained within wells in the depths of Brennenburg Castle. However as the events of the Dark Descent unfold, the Shadow following Daniel consumes room after room, until it causes structural failures that allow the deadly Kaernk to escape.
The Kaernk is only capable of attacking things that wander into the shallow pools that it inhabits. However, what it lacks in reach it makes up for with its invisibility. Daniel can only see where the monster is by the loud splashing noises, the water particle effect it makes when moving, and the banging it makes on doors when trying to break them down. It can be assumed that the creature is blind, as it will move toward any disturbance in the water, allowing Daniel to create distance between himself and the Kaernk by throwing objects such as books. However, if meat is thrown, the monster will behave differently; it will pursue and devour, buying Daniel a short amount of time to move in the water. If Daniel does not disturb the water after throwing an edible object, the Kaernk will return to where it was after it has finished eating, whereas if a book is thrown the creature will remain where it landed.
The Kaernk is encountered a total of six times, four of which are purely visual encounters with no actual threat. Daniel can catch a glimpse of the creature early in the game, as it splashes about below the grating on the floor of the chemical laboratory. The second and most dangerous encounter occurs in the flooded Archives, where Daniel must evade two of the creatures in two areas in immediate succession.
Upon leaving the Flooded Archives, you encounter another Kaernk in a chase to exit the area. This Kaernk is larger but slower than the first, hiding on boxes will do you no good as it can reach you easily and kill Daniel instantly. Daniel must slow it down by closing doors behind him in order to escape it alive.
Much later in the game it is encountered for a fourth time, in the Cistern. The only sign of its presence is its growling and splashing, but it is merely a hallucination. You can find out if it is a hallucination by throwing a rock in the water and looking for movement.
As Daniel explores the Sewer, he’ll come across a passageway that the Shadow has caused to collapse completely. Once there, he’ll hear the watery predator growl. It seems that the Kaernk is trapped in the rubble from this recent cave-in as it is unable to enter the area and attack him. In low sanity, Daniel may “see” a Kaernk following him.
The final two encounters occur during the quest to recreate Agrippa’s Potion, during which you will encounter a well-dwelling Kaernk. To obtain a sample of Tampter, Daniel lowers a haunch of meat into the well and allows the Kaernk to feast on it. If Daniel does not do this at the first well, he will have to do so at the second well located near the Cells. Falling into a Kaernk-containing well is fatal, similar to falling off a ledge in the Choir.
Essentially, he’s an invisible monster that can kill you only when you’re in water. He’s attracted by sound and movement. (I’d suggest something to throw and distract him from your path. Smart way.)