"Secret passageways" refers to hidden or concealed paths or corridors that are not easily seen or known by others. They are usually kept secret to allow for discreet movement or privacy. Full definition
Get to the Mayan Village through secret passageways hidden in the jungle. (xcaret.com)
As guests weave and wander, discovering secret passageways and hidden mysteries, each interaction that they have helps to unfold the mystery and is all part of a larger non-linear narrative. (visualnews.com)
She proceeded to mark out places where bombs would open new caves, bushes would reveal secret passageways and where I should go first. (buttonmashing.com)