Bare labyrinth

Bare rock and nothing green: a maze of passages worn by water over a million years or more, which branch, rejoin, climb, drop into shafts and end in mud. There is no light at all, the air is cool and still and smells of wet stone, and the only sounds are dripping, a distant stream and the party’s own breathing. Pale blind crickets, spiders and fish live on what the water carries in, and larger things hunt them, and travellers. The longest cave known, Mammoth Cave in Kentucky, is a maze like this more than six hundred kilometres long; people come for what lies beyond, and mark their way.

Light
Dark
Going
Hard

Going down

How warm the rock is and whether this place can grow there, under a temperate land: the deeper, the hotter.

Near the surface (50 m)
11 °C, it grows
A few hundred metres down (400 m)
21 °C, it grows
A kilometre down (1 km)
38 °C, it grows

Hear it

Hazards

  • Darkness. No light at all, ever. A dropped torch that goes out in a puddle is the end of seeing. D&D 5e: Beyond the party’s lights the cave is in Darkness and Heavily Obscured: a creature trying to see into it has the Blinded condition. A torch or lantern gives Bright Light around it and Dim Light further out, where Wisdom (Perception) checks that rely on sight have Disadvantage. Darkvision turns Darkness into Dim Light within its range.
  • Lost. Every junction looks like the last one. After an hour, nobody is quite sure which way is back. D&D 5e (House rule): Our rule: a party that neither marks its way nor keeps a map makes a DC 13 Wisdom (Survival) check each hour; on a failure it loses 1d4 hours finding a passage it knows again. Chalk marks or a careful map make the check needless, until something rubs the marks out.
  • Squeeze. The passage narrows to a slot to be crawled on one’s side, packs pushed ahead, with the rock pressing on the chest. D&D 5e (House rule): Our rule: in a squeeze every foot of movement costs 2 extra feet and no creature can take a Reaction. A Medium creature in armour heavier than Light makes a DC 13 Strength (Athletics) check to force through; on a failure it is stuck until someone helps it out, which takes 10 minutes. Large creatures cannot pass.
  • Sump. The passage dips under water and comes up again somewhere ahead. How far, nobody knows until they try. D&D 5e: A creature can hold its breath for 1 plus its Constitution modifier minutes (at least 30 seconds). After that it gains 1 Exhaustion level at the end of each of its turns, and loses them all once it can breathe again. Our addition: a short sump takes 1 minute to swim, and a rope tied through it makes the way back safe.
  • Shaft. A shaft opens in the floor of the passage, black, breathing a cold draught. Stones dropped into it take a long time to land. D&D 5e: A creature that falls takes 1d6 Bludgeoning damage for every 3 m (10 ft), up to 20d6, and lands Prone unless it took no damage. Our addition: the first creature to walk with a light, or a DC 12 Wisdom (Perception) check in the dark, sees the edge in time.

A scene

  • Simple Cave. The cave murmurs and sighs. A slow, cycling breath that carries no warmth and no explanation. Deeper within, water chooses to occasionally drip. The dark is total beyond the reach of any flame. Somewhere above, or perhaps below, something shifts in the stone. This cave is not empty. It is never empty. And it is never full. The full generator on the blog

Adventure hooks

  1. A party of cavers marked their way with arrows of soot on the walls. Someone has been adding arrows since, in the same hand, and they lead somewhere else.
  2. A mapmaker has spent twenty years drawing the labyrinth and is three passages from finishing. He is too old to crawl through the last squeeze, and he will share the map with whoever does it for him.
  3. Bare footprints in the mud lead deeper, small ones, made since the last flood. The village above has no missing child, and the prints are too narrow for one.
  4. Each spring the stream in the lower passages rises and seals them for a month. A fisherman who sells blind cave fish to a wealthy collector wants one last trip before the water comes, and the rain started this morning.

What may happen

  1. A breath of air on the face, from a crack too narrow to pass: beyond it, somewhere, there is another way out.
  2. Arrows smoked onto the ceiling with a candle, long ago. Some point the wrong way.
  3. A clear pool holds pale fish without eyes, which do not flee from the light.
  4. Huge bones in the mud of a dead end, washed there by a flood long ago.
  5. The sound of running water grows louder each minute, and it comes from above.
  6. A shout comes back three times from three directions, then a fourth time from nowhere.
  7. A body curled up in a side passage, a burnt-out lamp beside it and a map in its hand.
  8. A frozen waterfall of stone, cream and orange, fills the passage from floor to roof. Getting over it means breaking it.
  9. Pale crickets with legs far too long cover a wall and wave their feelers at the light.
  10. A clicking in the dark, like someone tapping a stone. It stops when the party stops.
  11. A small cairn at a junction, with a note pushed under the top stone.
  12. Bare footprints in the mud, the size of a man’s, and no soot on the roof from any torch.
  13. The walls are scooped into ripples like sand on a beach: fast water shaped them, and every ripple leans the way it flowed.
  14. Wet silt covers the floor, smooth as a sheet and untouched. Nothing has walked here since the last flood.
  15. White petals of gypsum curl out of a dry wall like flowers made of sugar. They crumble at a breath.
  16. Air moves in and out of a narrow passage in slow pulses, a breath every few minutes, as if the cave were asleep.
  17. A cross scratched on a rock with numbers beside it, and another visible further on: a surveyor’s marks.
  18. A young man with a rope coiled over his shoulder has been waiting at a junction for a day. He asks the party to look out for his partner, a woman with a red lamp.
  19. The way ahead is plugged to the roof with fresh mud from the last flood. Someone has started digging, and left the shovel.
  20. Far below, the stream murmurs like a crowd of people talking, just too faint for words.
  21. Leaves, twigs and a dead rat are wedged in a crack in the roof, high overhead: the last flood filled this passage to the top.
  22. Handprints in old soot mark a junction, one beside each way out, and each hand shows a different number of fingers.
  23. The floor is worn into a smooth groove down the middle, as if by many feet over many years. There are no tracks in it.
  24. A side passage is warmer than the rest and smells faintly of smoke.
  25. Far down a shaft a small light burns steadily, where nobody could have climbed.

Creatures

A town here

A city can live down here, fed by what grows below. Build it in Hearth

To bring back

Bat Guano, Brutacian Lung, Bugbear Tooth, Deep Gnome Nose, Fire Beetle Glands, Hart's-tongue Fronds, Free-tailed Bat Guano, Mycelium, Obsidian Powder, Ooze Portion, Scorpion Venom, Sulfur Pinch, Topaz Powder, Tourmaline Powder, Troglodyte Thumb Nail, Amber Tears, Amethyst Powder, Aquamarine Powder, Black Powder, Bloodstone Powder, Chalcedony Powder, Chitine Silk, Cockatrice Liver, Crystal Powder, Drow Hair, Echo in Stone, Ettercap Mandible, Ettin Toe, Firenewt Bile, Fixed Nitre, Galeb Duhr Soul, Giant Spider Perfect Eye, Jade Powder, Jasper Powder, Jet Powder, Lapis Lazuli Powder, Magnetite Shavings, Malachite Powder, Moonstone Powder, Myconid Spores, Oilbird Fat, Phase Beast Heart, Ruby Powder, Sapphire Powder, Selenite Sliver, Native Sulfur Crystal, Tanzanite Powder, Young Dragon Tonsils, Zircon Powder, Ankheg Antennae, Barghest Fang, Basilisk Throat, Cranium Rat Brain, Cyclops Eye, Drider Tongue, Edible Bird's Nest, Flumph Hypothalamus, Grell Beak, Kuo-Toa Gill, Mind Flayer Brain, Minotaur Heart, Ogre Liver, Phase Spider Egg, Troll Bone Marrow, Beholder Eye, Deep Lantern Organ, Dragon Tonsils, Gorgon Muzzle, Oblex Slime, Oni Liver, Roper Bile, Shadow Mastodont Eye, Tainted Quaggoth Soul, Aboleth Eye, Adamantine Dragon Tonsils, Alhoon Brain, Amethyst Dragon Tonsils, Iridium Powder, Elder Oblex Slime, Purple Worm Bile, Sapphire Dragon Tonsils, Shadow Dragon Gland, Tarrasque Carapace Piece, Topaz Dragon Tonsils, Tungsten Powder, Wyvern Poison

Elsewhere below

Fungal forest, Doline jungle, Glowing meadow, Lava tubes, Sulphur cave, Crystal caverns, The abyss

This work includes material from the System Reference Document 5.2.1 ("SRD 5.2.1") by Wizards of the Coast LLC, available at https://www.dndbeyond.com/srd. The SRD 5.2.1 is licensed under the Creative Commons Attribution 4.0 International License, available at https://creativecommons.org/licenses/by/4.0/legalcode.

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