Potomac River

Mather Gorge is a river gorge south and just downriver of Great Falls in the state of Maryland bordering Virginia. 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. Both parks are National Park Service sites.

Bear Island is an island located in Potomac, Montgomery County, Maryland between the Potomac River and the Chesapeake and Ohio Canal near the Great Falls. It is managed by the National Park Service as part of the Chesapeake and Ohio Canal National Historical Park and is co-owned by The Nature Conservancy.