Narrow passages are like most others except that they are thinner and only certain characters can enter them. Narrow passages run vertical, as opposed to small passages, which run horizontal. They are often composed of the same black material which makes up most of the game's world.
Narrow passages pose no threat, but only a hinderance in progression in the game. It blocks wider characters, such as Sam or Claire, from moving further along in a given level and requires certain characters to access them. Occasionally, however, narrow passages can prove to be quite useful, especially in levels involving a character who possesses poor jumping abilities, such as Chris, along with a tall character, such as John. By dropping into a narrow passage, the taller character becomes much easier to jump over.
Overcoming narrow passages are a simple task. A certain character must be brought to the narrow passage and enter, exiting on the opposite side of the passageway. Only thin characters can be used to enter a narrow passage.