They are a dismembered branch of the great Appalachian family, and are seen away to the west of the river, swelling up to a noble height, and lording it over the surrounding country.

At the beginning of the story, the Kaatskill (Catskill) Mountains are introduced as the setting. The prose describing them is grandiose and mythic, providing the story with a setting as impressive and unlikely as its plot. The mountains are mysterious, mercurial, and unknowable, much like the events they will host throughout the story. 

He saw at a distance the lordly Hudson, far, far below him, moving on its silent but majestic course, with the reflection of a purple cloud, or the sail of a lagging bark, here and there sleeping on its glassy bosom, and at last losing itself in the blue highlands.

The Hudson River, as viewed by Rip during his infamous trip into the woods, is an important part of the landscape of the region. The man for whom it is named is also an important figure in the story. It is Hendrick (Henry) Hudson whose party of abandoned spirits Rip encounters in the forest. The ancient explorers are now doomed to haunt the area surrounding the site of their betrayal by others.

Passing through the ravine, they came to a hollow, like a small amphitheatre, surrounded by perpendicular precipices, over the brinks of which impending trees shot their branches, so that you only caught glimpses of the azure sky and the bright evening cloud.

The forest climbing the mountains is portrayed in ever more disorienting language as Rip travels further into it, carrying a keg. The sense that the landscape has become more dreamlike and less recognizable adds emphasis to the strange figures that Rip encounters. The forest has taken him in, ushering Rip into a world completely removed from his own, if only for a while.