Parts of the self that are unexplored. Untapped potential and resources. It may be time to go on an adventure and do work on yourself for self-discovery. Much needed mental or emotional retreat. A sanctuary, or a haven where you can hermit away for awhile and escape problems. A much-needed hideaway where you can avoid feeling pain.
See Hermit, Self-Discovery, Black, Shade, Dark, Tunnel, Shadow, Blackout, Unknown.