General Synonyms:
* Isolated
* Remote
* Hidden
* Lonely
* Private
* Quiet
* Solitary
* Secretive
More Specific Synonyms:
* Unexposed: emphasizing the lack of visibility or access.
* Sheltered: suggesting protection from the outside world.
* Inaccessible: emphasizing difficulty of reaching the place.
* Desolate: implying a feeling of emptiness and lack of life.
* Withdrawn: suggesting deliberate separation from society.
The best synonym will depend on the specific situation and the tone you want to convey.