It's Not a Lake is one of the Collectibles found in Alan Wake 2. It is one of the pages of the Return manuscript. It can only be found in the New Game Plus mode "The Final Draft."
Transcript[]
The surface of a lake was a black mirror. The upside-down reflection identical, yet darker. A window into a darker world than ours. A doorway. A hush so profound, it rang like a scream. As if the last echo of the terror had just died. Inside the steep cliffs of the caldera, everything echoed. An echo chamber. Like a fractured skull.
A shadow fell on Cauldron Lake. Something of impossible scale loomed over it, blocking the sky. Ahti, the janitor, leaned close. Took a hold of the rim of the crater. Lifted up his janitor's bucket. The water sloshed. Swirled inside like a vortex. Gently humming a tango, he poured the water on the attic floor.
Location[]
The page can be found on the pathway leading to Cauldron Lake, right before reaching the lake shore, after the point of no return.