Secret passages or hidden corridors, represented by , are a type of terrain that appear to be solid rock until exposed, when they turn to an ordinary corridor.
When a room and corridor level is generated, secret passages are often created on some corridor squares. You can sometimes guess the existance of a secret passage from surrounding corridor squares, especially if they are at a corner, but corridors can also have natural dead ends.
Until exposed, a secret passage doesn't only look like solid wall, but also acts like one: monsters (including pets) won't step on a secret passage square, the square blocks thrown objects, and you can't see through them.
Exposing a secret passage
There are multiple ways to expose a secret passage, turning it to an ordinary corridor square.
- The search command or the automatic searching property has a chance of finding them: see searching for what influences the probability.
- Apply a stethoscope at them.
- Read a blessed scroll of magic mapping.
- Cast the spell of detect unseen or zap the wand of secret door detection when you're near the corridor.
- Start to dig the secret door square.
- Kicking can expose them sometimes.
Secret passages are more difficult to expose than secret doors, as effects that would usually open or break down a door (multiple wands or spells) do not work on them.