Permafrost Sea

The permafrost sea is a lake west of the Ice-peak Concord and north of the Lightfoot Land. he vast majority of the year, the lake is covered in a thin layer of ice, giving it its name of permafrost sea. Boats that sail this lake are built to be able to break this layer of ice.
Due to its frozen nature, the cove is often used as a shortcut during the winter when the ice is thicker, whole caravan traveling on the snow and ice.

Type

Lake

Features

Frigid Water. A creature can be immersed in frigid water for a number of minutes equal to its Constitution score before suffering any ill effects. Each additional minute spent in frigid water requires the creature to succeed on a DC 10 Constitution saving throw or gain one level of exhaustion. Creatures with resistance or immunity to cold damage automatically succeed on the saving throw, as do creatures that are naturally adapted to living in ice-cold water.
Slippery Ice. Slippery ice is difficult terrain. When a creature moves onto slippery ice for the first time on a turn, it must succeed on a DC 10 Dexterity (Acrobatics) check or fall prone.
Thin Ice. Thin ice has a weight tolerance of 3d10 × 10 pounds per 10-foot-square area. Whenever the total weight on an area of thin ice exceeds its tolerance, the ice in that area breaks. All creatures on broken ice fall through.