Lake Fahrenheit is a massive lake located between the city of Mantle and the city of Atlas. It covers several hundred miles and is known for being one of the most dangerous areas within Atlas. For one, it is frozen over, making footing very unstable and giving way to the risk of being trapped underneath it should you fall through. On top of that, grimm are constantly traversing the lake's surface, and the lack of areas to hide have made it incredibly dangerous for caravans. Additionally, parts of the lake's surface have accumulated snow so much over the decades that it is hard to distinguish whether some parts of the lake are really just land or not, causing many people to accidentally step onto unstable parts of its surface when they are not careful.

The most abundant grimm that inhabit this lake are Boarbatusk. Given that Boarbatusk are most prominent in Atlas, it is only natural for them to be found throughout the continent. Additionally, there are tales that creatures dwell within the water, waiting for strong enough prey to arrive so that they cn fight them. They have never been properly seen but some have reported seeing a shadow large enough to span several miles underneath the surface of the lake.