Adjectives

(s)concealed, hidden, out of sightnot accessible to view“concealed (or hidden) damage”, “in stormy weather the stars are out of sight”
(s)hidden, secretdesigned to elude detection“a hidden room or place of concealment such as a priest hole”, “a secret passage”, “the secret compartment in the desk”
(s)hidden, obscuredifficult to find“hidden valleys”, “a hidden cave”, “an obscure retreat”