Mountaineer's Ale

SS undefined (Wetlands)

Mountaineer's Ale is a quest item for The Stolen Keg.

Source
There may be several places it can be found, but one of them is on the top level inside the Dun Algaz stronghold in Wetlands.

It is also used in the followup quest, Keg Run, where the PC takes it to Slabchisel's Survey.