Found on the border where the world borders between the cold and the artic, it is a lake consisting of a viscous substance that cannot support life and with so little density that it is impossible to swim in.
In the center of the lake is the island Yutan, a most mythical island with almost no peer. Many try to make it to the island. Very few succeed.
This is because there is no natural air draft to allow flight and a boat cannot float on the surface. The only known way is to wait for night, where the temperature difference is enough to freeze the mystery substance.
Unfortunately, this time of night is when the Yotes come out to hunt: Massive monsters that travel in packs and only one when is needed to tear a person limb from limb. Also considering that the travelers who make it never return, Yutan remains both a place of legend and danger.