Secret passage

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 to find 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.