Kalinag's Descent is a cave located north of Varshakot , it is referenced in a letter found in a house north-east of Varshakot.
The bottom of Kalinag's Descent is filled with water, and on the north side is a closed golden door.
Here, one of the 20 lost letters can be found halfway down the cave after climbing upwards twice with the grappling hook along with some small ammo stacks and a statue of a face covered in something blue identical to the one on the surface.
In the water skeleton's can be found along with 3 loot-filled chest's. However, there is a demon fish in the water.
On top of the water a blue plant can be found.