The world this is set in is located in a valley and doesn't allow anyone to leave.

They are very strict about this so there are many watchtowers along the top of the valley sides, and soldiers patrolling the area just outside of the valley (where the secret tunnel leads) to ensure no one leaves.

As a part of the story, the main character has a secret tunnel that leads out of the valley, into the forest on the outside (it goes through the mountain side.) I'm concerned about how she keeps this completely secret for a long period of time, without anyone either noticing her go through the tunnel, or the tunnel itself being discovered.

For extra context, the technology is not advanced at all, think of how it would've been in medieval times; so there's no cameras etc. The only way someone would find out is if they saw it with their own eyes.

This tunnel is one her grandmother made with a group of others a number of years before the main character uses it herself. This means it has to have been effective at being a secret for a long period of time.

I was thinking leaves to cover it, or some rock contraption which makes it secretive- but none of these seem to work, so I'm in great need of a second point of view.

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    $\begingroup$ Nothing can beat entrance behind the falls (TV Tropes warning). $\endgroup$
    – Alexander
    Mar 11, 2022 at 19:23
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    $\begingroup$ Big problem I have with a human made tunnel. Where are they putting the excavated material. Because thousands of cubic meters of material doesn't hide well.What about a natural cave system in a karst formation? $\endgroup$ Mar 11, 2022 at 20:03
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    $\begingroup$ @GaultDrakkor Ooo I never thought about that before, thank you for bringing that into light! I really like the idea about a natural cave system though- definitely something I'll think about more! $\endgroup$
    – Faeology
    Mar 11, 2022 at 20:23
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    $\begingroup$ @RobbieGoodwin The cave isn't story, it is a plot device. The problem is making a believable cover for it. That's a world issue. $\endgroup$
    – Vogon Poet
    Mar 14, 2022 at 1:13
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    $\begingroup$ definitely don't have a famous folksong about two lover using it to meet each other despite living across the mountains $\endgroup$
    – Tristan
    Mar 14, 2022 at 11:19

8 Answers 8


The other answers cover how to stop someone just randomly turning up, but not how to stop a dedicated search team that tracks her down.

There's an alternative. The protagonist's family made an underground tunnel around a river. The river doesn't always have air, and has many twists you can get lost in. Only someone with detailed knowledge of the routes can pass it.

Even if someone tracks her down and finds the underground river, they are likely to get lost and drown in it. She holds the only map in her head, and she's not telling.

enter image description here

The entrance would be a river which seems to go into a rock wall. She would know she can swim under the surface and go into a hole above the entrance, while someone who tried to follow the stream would die, and would know all the twists and turns needed after that. Underground there would be a mix of cave systems, artificially made rooms for smuggling, and a path to the other side. Someone who followed her would just see her vanish into the river, and if they followed her would just get lost in the river.

Some sections would have holes just narrow enough for water, but not for air. You'd have to swim through them, or bypass them with other tunnels made. The protagonist would know how to get through, others would not.

Exploring the tunnels was a decades long effort by her family, and not something a foe could quickly do.

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    $\begingroup$ Cave dive with no scuba gear, whoa-uh-oh, we got some wild, wild life... Picture a cenote that is a water source and a playground to stay cool in the summer, but also extends into a mostly underground cave system that goes vast distances with only occasional accesses to air. And you'd better know where they are... in the dark, unless you have a medieval undewater torch to use. $\endgroup$ Mar 11, 2022 at 22:12
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    $\begingroup$ I added commentary on it. The entrance would be underwater, so someone tracking her would just see her vanish into the stream and never surface. If they did track her and go inside they'd have no idea where the tunnel was and where dead ends were that would leave you trapped in a stream were, and would probably die. $\endgroup$
    – Nepene Nep
    Mar 11, 2022 at 23:36
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    $\begingroup$ Best. Graphic. Ever. 👊 ( ⊙ ﹏ ⊙ ) $\endgroup$
    – Vogon Poet
    Mar 12, 2022 at 5:04
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    $\begingroup$ Yah +1 for the illustration alone! $\endgroup$ Mar 12, 2022 at 17:03
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    $\begingroup$ @ChrisH If this is a karst formation riddled with holes there's no need for material removal in the first place--there will be plenty of holes inside to toss the rubble down, they don't need to pull it out. $\endgroup$ Mar 14, 2022 at 21:56
  • Have the tunnel start in the family cottage.
    Could be a root cellar, or a more traditional masonry basement, or hidden under the floor. For a medieval setting, how about under the open hearth, or perhaps under the dung in the chicken pen?
  • Then there is the hole under the outhouse. Searchers might be reluctant to go in there.
  • Have the tunnel branch off from a masonry well above the water table.
    It is cleverly constructed so that one would have to climb down to spot it, yet there is a ready, inconspicuous rope already present.
  • Make it reasonably common to use natural caves for storing cheese, etc., and make them the personal possession of wealthy farmer's families. Except that one goes deeper than the rest.
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    $\begingroup$ Upvote for the cheese idea. Because the main character is a cheese maker! $\endgroup$
    – Willk
    Mar 11, 2022 at 21:28
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    $\begingroup$ Then there's this: roadsideamerica.com/story/62539 for more ambitious purposes. $\endgroup$ Mar 12, 2022 at 12:13
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    $\begingroup$ The Lone Ranger's silver mine was accessible inside an ordinary-looking cabin! $\endgroup$ Mar 13, 2022 at 20:52
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    $\begingroup$ The cave doesn't even have to be private. If a random person wanders around the cave for 30 minutes and hasn't even reached the "secret" door, then you don't have to worry much about passersby who have no good reason to go spelunking. $\endgroup$ Mar 13, 2022 at 20:55
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    $\begingroup$ Bottom of the well is another good example, and less gross than under the outhouse... $\endgroup$ Mar 14, 2022 at 15:39

Mountain passes are infamously hard to traverse. Especially in a preindustrial culture, most people would religiously stick to the established passes and trails just because it’s too risky to explore a different pathway. You don’t want to take a POTENTIAL shortcut and end up falling off a cliff, or getting turned around and ending up in miles of wilderness.

Her grandmother could easily have discovered a cave tunnel that was formerly blocked, but got revealed after a landslide, or after a warmer winter where more snow/ice melted than usual, and the knowledge of the tunnel would have been guarded very strictly by a handful of trusted family friends.

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    $\begingroup$ "Three may keep a secret, if two of them are dead." $\endgroup$
    – Zeiss Ikon
    Mar 11, 2022 at 20:15
  • $\begingroup$ Ooh yes I absolutely love this idea! I was wondering if it would be a bit difficult for her to build an actual tunnel through a mountain- but the idea about it being a cave system formerly blocked off works brilliantly! Thank you! $\endgroup$
    – Faeology
    Mar 11, 2022 at 20:26
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    $\begingroup$ Oh right, I overestimated “handful of family friends.” I’d say you tell ONE family friend plus their younger relative, especially if the original friend is close to Grandma’s age. You need a balance between keeping the secret, and accidentally losing the knowledge of the tunnel completely. $\endgroup$
    – Jamie L.
    Mar 11, 2022 at 20:50
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    $\begingroup$ Cave paintings! The formerly blocked off cave needs ancient cave paintings. She has names for some of the painted animals and she talks to them when she goes thru. $\endgroup$
    – Willk
    Mar 11, 2022 at 21:37

“Dear, let me say something about this old tree here. It has a story to tell. Walk over with me, just through these bushes.” —- We go back to a day, many years ago, Nana was helping at the cottage and needed some clay for bricks to patch the fireplace. Her papa sent her down to the river, where the mountain washed down lots of silt and clay into the valley. She went with a bucket and a shovel to carry as much clay as she could, because the fireplace had settled and was cracking at the bottom.

She arrived at the river and came to a small tree, which was tenuously clinging on to the river bank, refusing to let its little piece of soil wash away. Roots were washed bare by the water at the river’s edge, and the little tree dug them firmly into the riverbed to keep itself righted. But something else was odd at the base of this tree. The water below the roots was in a swirl. She loved the pretty funnel it made, and started dropping leaves into it. They spun around and around.

She leaned over, just to get a closer look, and the soft, cool clay of the bank would not hold her. It crumpled down into the water… and disappeared! She noticed that the little whirlpool now was a little bigger too, and her leaver were gone! She started to put more leaves in, and through the gurgling sounds of the water, they were sucked down into the earth.

“Where could these leaves go?” she wondered. She gathered her clay for her papa, and ran back to the cottage.

A week later, she returned to the little tree with a long branch she had picked up along the forest path. The path does not go out here, but it isn’t far away. Only a few shrubs line the foot of the mountain where the river is forced to turn. She pulled up her skirt, and stepped into the cool water. It was only midway up to her shins, but moved fairly quickly. She poked her branch into the whirlpool. It went in several inches, and felt like it caught a root from the little tree. She wiggled it around some more, and then it almost fell into the ground! There seemed to be no end to the hole now.

“Where is the water going, I wonder?” She pushed the branch in all the way, stepping closer to the edge, carefully. The stick felt like it was in open water with nothing below it at all. This was spring, the water was still cool from the fresh melt. She decided to come back when it was warmer out.

Several weeks went by and she gathered up a rope from her papa’s shed. She walked out to the woods, and the path had nearly overgrown by now. it took a while to find her little tree, by stepping through some scratchy and prickly overgrown shrubs. But she found her tree, and below it; the little whirlpool.

She tied the rope to the little tree, and the other end she looped around her waist. Then she took off her skirt which was covering her bath clothes. She stepped into the water. She was very scared, but also very curious. This was her greatest fault, her papa thought. She carefully walked up to the whirlpool, feeling the smooth river stones between her toes. As she got closer, she was very nervous that the earth may fall in again like the first time. But she had a rope on, and that gave her courage. She moved up, just to the part where the water turned black with nothingness, and her toes dangled over the edge. It felt firm. It felt like solid stone, as if she were a mud doll on a large granite shelf. She gave herself a bounce.

There was no question, this was a very solid footing. Looking around, making sure no one was watching (she had a bucket for an excuse just the same), she got to her knees and sat in the shelf, in the cool summer water. Her feet dangled down into open water, just like the branch. The little whirlpool twirled gently just in front of her, and she could cup it in her hands.

She looked around again, and seeing no one, she took hold of the rope where it was fastened to the little tree. Pulling it taught, she gently slid herself off the stone shelf, and held herself above the hole with her arms. The coarse shelf of stone scraped against the back of her thighs with only her cotton undergarment protecting her, but still, there was no bottom. Her waist was just under water now! She decided to slowly unfold her arms to lower herself into this dark, strange hole under the tree. Deeper it went. Now the cool water tickled her rib cage, but her feet still swung free. She lowered to her chest now, and nothing! At this point, she wanted to be sure she could get out, so she pulled up a little. Relieved, she found that she was very light in the water, and pulling up was not difficult. Now was the worst part, to put her elbows at a right angle, she would be into the water up to her armpits. This was a scar as she would go!

And, as the water tickled the bottom of her armpits, something touched her toe! Quickly, she pulled up again and brought her feet up with a startled shriek! Now she has to check around again, that no one saw or heard her. It seemed she was not noticed.

She thought long about this. Did something brush her, or did she touch something? Nothing is reaching up to grab her. OK, now she got the nerve to find out. She lowered herself down carefully, reaching around with her toes. Then, just as before, something touched her toe. Did it move? she thought? No, it’s not moving.

With a little more confidence, she touched the thing with her toe, then lowered her foot down flat. It was something solid. Her weight, light as it was, seemed to be supported. Finally, she let the rope go. She was standing in the hole in water just below her shoulders. But where does the water go?

She tugged firmly once again at the knot on the little tree. It was a good knot, like her papa taught her to make. She bent her knees down, and pushed her hands into the dark water, clenching on to the thick roots of the tree for stability. Lower she went, until her chin touched the water. It was like the water in her bath after playing for an hour. No, maybe a little colder than that. Now she realized that she forgot to tie up her hair. It was wet like a mop now at her shoulders, but frizzy up top. This was uncomfortable. She had the urge to just wet it all and let the weight of the water straighten it out. She went under, and the hole swallowed her up completely.

It felt cool but not frigid under her, she braved to open her eyes. Nothing at all but blackness met her. But more frightening, her hands could feel nothing in front of her below the roots either. There were coarse rock outcrops to the left and right, like pinschers holding the tree up from the earth, but nothing straight ahead. Her left hand held the rope tightly, and she drifted weightlessly forward following the soft current and paying out the rope slowly. This was a time to use her bedroom closet trick: Think about nothing. Focus on her body only; the braids of rope passing through her hands, the gently waving fabric of her blouse brushing her sides, the long locks of hair tickling her shoulders. Thinking about where she was right now would be bad. It is a bad place to be.

Her lungs told her it was time to get up to the surface. The sound of the gurgling river dimmed behind her, but a new sound caught her ear up ahead. She has no idea what direction she went, but the mountain was very close. Is that another river I hear? She decided to push forward one more kick before turning back; the rope gripped tightly in her hand now.

Her hand pushed forward with one last lurch. She really wanted something to be here—anything to make this journey fruitful. Her hand flailed just a bit, and felt the coarse, wet stone walls around her, until her hand made a splash, just over her head! There was air above her! Would she dare to taste it? There was no longer a choice.

She had no choice now. This little air was the closest she had, and it could refill her for the trip back. She pressed her face upward, and blew out her lungs with relief. In came a draft of cool, earthy air. It was a shallow cave… or maybe a shallow entrance to a cave?

She took a few breaths, and felt relaxed. Opening her eyes was useless, it made no difference. But she had air now, and her rope. She pressed further. The cave rose up.

She reached a point where she could swim openly, in chest-deep water and a clear ceiling. She kept one hand over her head in case something hard was sticking down. It never came. But what did come, is a shore. She had never in her life been more terrified. She had never in her life been more thrilled. She had never in her life, been this curious.

She returned a week later, with some kindling and a cloth soaked in oil. She wrapped them in wax parchment, bundled them tightly, and covered the bundle with wax. Having this portable fireplace secured against the water, she lit the fire in her secret cave. She followed a river through the mountain for a while, but it went down, and the cave went straight.

It went straight through, to freedom.

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    $\begingroup$ That is absolutely amazing! I love the storytelling aspect you incorporated here, it's perfect! This has also greatly inspired me for my story in so many ways, thank you so much! $\endgroup$
    – Faeology
    Mar 12, 2022 at 18:05
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    $\begingroup$ It was a subjective question and became harder to “tell” than to just “show.” $\endgroup$
    – Vogon Poet
    Mar 12, 2022 at 19:07
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    $\begingroup$ Beautiful story! I'd give +10 votes if I could. $\endgroup$
    – FZs
    Mar 13, 2022 at 15:42

In order of plausibility,

Option #1 bats cave

The entry is in a bats cave. Soldiers fear bats (superstition) grandmother did not.. and she tells her

Option #2 The entry is up a hollow tree

There's a hollow tree in her back yard. The opening is 5 meters up, and on the inside, there is a ladder going down to the entry of the tunnel. All you need to do is climb the tree and descend. You can do that at night and not be noticed. Soldiers are not interested in dead trees.

Option #3 Grandmother invented bear spray

The entry of your tunnel is in a bear cave. An underwater river flows through it, with plenty of fish to feed a family of bears thriving there. The soldiers won't dare to enter this cave.

Grandmother found a way to handle the bears.. and after a while the bears got to know her and avoided her, so she does not need to use it often. She left a good supply of it in the kitchen cabot.


A few random ideas:

  • A place, which seems to be dangerous because of surroundings, but contains a secret. Eg. a cliff edge with some bushes covering the fact, that there's a stone shelf below leading to a cave. Hidden in plain sight, because no one would go there (adjust the idea to the valley and its shape).
  • A hidden passage inside a hidden passage. Even if someone discovers the first one, probably wouldn't search for a second one. That's a derivative of hiding something in the ground with something of less value buried just above. When people reach the topmost object, they'll most likely stop searching further and the deeper object remains safe.
  • If "magic" is allowed, there may be a physical anomaly, which allows reaching otherwise non-accessible area (local decrease of gravity, for instance).

I suppose that placement of the secret way itself is a simpler part, what's harder is how to cover up, why someone walks somewhere and doesn't return. So most likely it should be a place, where prolonged disappearance is justified (eg. home, library, hotel, etc.).


Hiding a tunnel is easy, keeping mouths shut is the hard part.

No matter how well you hide your tunnel, the real challenge over this period of time is keeping people from talking about it. At first it might be your Grandmother and her friends who knew about it, but then they started getting spouses and kids and more friends and grandkids and cousins etc. that they each start sharing the secrete with. After 3 generations there could be hundreds of people who know about the tunnel, and only one of those people has to be a loyalist to share its position with the guards who will destroy it.

The only way to keep the tunnel a secrete that long is to make it forgotten. So, perhaps when the grandmother and her friends built the tunnel, they hid it well enough to avoid physical discovery, but they were soon after found outside of the valley and executed before they could tell anyone else about the tunnel, or else, they ran away never to be heard from again.

So, fast forward 3 generations, and the woman would by chance discover what had been forgotten. Perhaps it is a secrete passage in her grandmother's old home that she happens across, or maybe the grandmother left a note in the margin of some old book that's been in storage for a very long time, or what not. As for the exit... caves can stay hidden in plane sight for a very long time. The dead sea scrolls stayed hidden for about 2000 years with no real effort to hide the cave entrance; so, even a cursory attempt to hide this tunnel could work for a very long time. Something as simple as an overgrown sink hole could stay undiscovered through centuries of patrols if its far enough away from any paths.


Terabithia style.

I like the other answers. There is one more. Your character escapes from her miserable valley using the secrets her grandmother taught her when she was a little girl. Her grandmother built her the tunnel but her grandmother did no digging. The tunnel is secret because the tunnel is only in her mind. She escapes to a place she can be free and so for a while, she is free.


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