Third Hill Mountain is a ridge in West Virginia’s Eastern Panhandle and the highest and most topographically prominent summit in Berkeley County, rising 2,165 feet above sea level. Near the place called the Locks-of-the-Mountain, it joins neighboring Sleepy Creek Mountain. Together the two ridges enclose Sleepy Creek Lake and the Sleepy Creek Wildlife Management Area. In the comparatively level landscape of the far Eastern Panhandle, they stand out for their height and shape. The Tuscarora Trail follows part of Third Hill Mountain along its ridge and bench, making it both a notable destination for hikers and a defining landmark in the surrounding countryside.