Cliff walls and hypothermia - Isle of Dread Rules (spoiler)

Location 3 on the plateau.

Cliff wall.
"The cliffs surrounding the central volcanic lake form a high, imposing wall of upthrust rock... Even characters without climbing skill may attempt the climb, as there are obvious handholds and routes up the rock face. For all characters except thieves, the base chance of falling is 50%. This may be reduced 10% if a thief is with the party (to give guidance), by 10% if the character's Dexterity is 15 or greater, and by 20% if the characters are roped together (the DM may further adjust the chance of falling depending on other party actions). It will take 12 hours of climbing time to reach the top of the cliffs. [No rules given for how often to check or what happens if a character falls.]

At the top, the rocks are covered with ice and snow, and the temperature is below freezing. No encounters will occur here, but characters who attempt to stay here overnight without warm clothing will suffer 2-12 points of damage from exposure."