Suppose there's somewhere you need to go, but getting there could be difficult or dangerous. Maybe you have to get into a walled city, castle, or Supervillain Lair, but the entrance is guarded by armed soldiers or a Golem. Maybe you have to cross a minefield or an uncharted deadly swamp where one wrong step could drop you into a pit from which you would never return. Maybe you've gotten into the enemy base and need to go to the control room, but you suspect that the main hallway with signs saying "control room this way" has more security cameras than all the other hallways combined. Maybe there's a range of mountains you need to cross, but your map doesn't show any pass nearby. Maybe you just need to go from one town to another, but you're a widely recognizable fugitive and don't want to be seen by other travelers on the road between them. Whatever the reason, there's somewhere you have to go, and obvious ways to get there either don't exist, would take too long, or would be near-suicide to use. If only there were some special route that's not widely known, one that could get you where you need to go while bypassing many of the obstacles in the way...
What you need is a Secret Path. This is a passageway that not everyone knows about that can be used to get somewhere that is difficult to reach or to go somewhere without being noticed. Sometimes a local guide will be knowledgeable about paths that outsiders are unfamiliar with.
Although these secret passages are sometimes lauded as "shortcuts," they can sometimes take longer than more obvious paths, and can be laden with treacherous hazards that make them even more dangerous than the danger they allow travelers to avoid. Expect any secret path through a swamp to be unpleasant, since Swamps Are Evil.
Common types of secret paths include back doors, Bookcase Passages, ventilation shafts, and underground routes such as passages through Absurdly Spacious Sewers. See also Right Under Their Noses, Hidden in Plain Sight. If you make your own secret path, it's called Dungeon Bypass.
- The Chronicles of Prydain book The High King. Achren leads the heroes along a hidden path over Mount Dragon into Annuvin, avoiding the dangers of other routes.
- In The Lord of the Rings:
- Gollum leads Sam and Frodo through the Dead Marshes, using a path that the orcs don't know.
- Lord of the Rings also has the path the Rohirrim take to get to Minas Tirith, led by Ghân-buri-Ghân.
- The hidden West-Gate into Moria, effectively a secret passage to everyone but the Dwarves... and their friend.
- Meanwhile, back in the Shire, young hobbits would occasionally search for hidden passages in Bag End, convinced that Bilbo has concealed his legendary wealth there.
- Cirith Ungol, a small, lightly-guarded, and seldom-used pass near Minas Morgul allowing one to enter Mordor without having to cross the Morannon and use the Black Gate itself. Gollum leads Frodo and Sam that way, where the Hobbits discover there's a very good reason it's seldom-used.
- The Hobbit has a Dwarven door in the Lonely Mountain that foreshadows the later book's Moria gate — a secret passage into the very heart of the Lonely Mountain whose keyhole only appears on the rarely-occurring Durin's Day and whose key was lost for years.
- In Space Marine Battles novel Fall of Damnos, Scipio's squad spends most of the novel looking for one to get close to Necron artillery, as all the easy ways are swarming with killer robots. Jynn provides one.
- The third Soldiers of Barrabas (a Heroes "R" Us series by Gold Eagle) novel had enemies of Nile Barrabas from his Vietnam days kidnapping his girlfriend and saying "You've got 48 hours before we kill her. Come and get her." The Big Bad thinks his jungle fortress surrounded by booby traps and ambushes will take care of Barrabas and his men, but they kill an ambush squad and infiltrate up their hidden retreat path, which is free of booby traps.
- When a Soul Hunter arrives on Babylon 5 he goes to the local crime lord and buys a guide to the secret ways on the station, to enable him to get close enough to Delenn to collect her soul.
- On The 100, Bellamy gets a detailed map of Mount Weather's air vents and unused passages, letting him get to places inside the Mountain while avoiding guards and locked doors.
- A Dungeons & Dragons campaign module includes a secret path intended to be the faster exit for the party, which spirals along the main path. The book suggests to prevent finding the outside path, to ensure that the player goes through the hazardous portion.
- Roguelike Omega included secret mountain passes, which cut down on travel time in the wilderness.
- Most instances of The Lost Woods in The Legend of Zelda series require you to traverse a very specific route to avoid being sent back to the entrance.
- In Skies of Arcadia, there is a passage through Valua's sewer system that leads to the arena in the Coliseum. The sewer system can also be used to travel from Lower City to Upper City, even though free travel from Lower City to Upper City is supposed to be forbidden.
- There are a number of these in The Angry Video Game Nerd Adventures, usually leading to a cameo and some items. Others end by unlocking Mike Matei and the Bullshit Man as playable characters. (Speaking of Mike, he can spot secret paths and destructible tiles, making searching a good deal easier.)
- Sewers are good for this; that's how the Gaang gets back into Omashu in Avatar: The Last Airbender. There's also supposedly a "secret river" (but not secret enough not to be discussed in Fire Nation grade school) that leads to the Fire Lord's palace.
- Disneyland is actually built above ground level. This is hidden by the terrain design. Underneath the park are passageways to allow employees to easily get from one part of the park to another more quickly than through the park itself.
- According to historians like Herodotus, Xerxes gained an advantage in the Battle of Thermopylae when a Greek named Ephialtes told him of a mountain pass around Thermopylae, at which point Xerxes secretly sent 20,000 Immortals under the command of Hydarnes through so that the Persians could have the Greeks surrounded.
- When naval minefields became a common tactic in modern war, the defenders would have pilots (small-craft captains) who could guide friendly shipping through a safe path. Assuming that none of the mines had come loose and drifted into the path you were using.