The Maryland land side of the gorge is Bear Island, part of the Chesapeake and Ohio Canal National Historical Park, and the Virginia side is part of Great Falls Park.
The gorge is named after Stephen Mather, the first director of the National Park Service.
The gorge is cut by the Potomac River and is, for the most part, lined on both sides by cliffs.
On the Maryland side, in the C&O Canal National Historical Park, Section A of the Billy Goat Trail follows the gorge—from below Great Falls to above the Anglers Inn river put-in.
Generally, most of the rock climbing occurs on the vertical cliffs of the Virginia side of the gorge, below the Observation Decks and above the 90 degree river bend.