Upper Devil Den Falls is the third and uppermost in a series of three significant waterfalls along Devil Den Creek, which is a large tributary of lower Panther Creek. The waterfall is 35 feet high and is located at the head of a steep gorge carved out by Devil Den Creek. It lies about 400 feet upstream from the middle falls (Devil Den Falls). 

Upper Devil Den Falls requires a much tougher scramble to reach than the first two off-trail waterfalls on this creek, so I believe this one is mainly for hardcore waterfallers. From the base of Devil Den Falls, this is an extremely steep climb up the overgrown and rocky hillside. Some may find it easier to approach Upper Devil Den Falls from Black Mountain Road (FR 139) to the south, though there is no trail from this direction either. 

For detailed directions, see page 263 in Mark Ozboyd's "Waterfalls of Georgia" guidebook.