Underdark Locations for D&D 5e Encounters

"The numerous beetles here live in symbiosis with several tall purple mushrooms. They are unaffected by the drifting poisonous spores. "

Tables for Wilderness, Semi-Civilised and Unusual Underdark locations. Result is from Underdark Unusual Locations.

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Underdark Encounter Locations

Underdark terrain is consists of twisting passages and grand caverns. Stalactites and stalagmites, fungal gardens, toxic pools and treacherous ledges mark the caves of the largest dungeon.

There is a 5e Underdark random encounter generator at ChaosGen. And a separate tool for encounter locations including Underdark.

There is also a pdf of these and more tables at the DM's Guild as Underdark Encounters.

Underdark Encounter Tables - creatures | locations | non-combat | complications

Underdark Wilderness Locations

1d8+1d12	Underdark Wilderness Locations
2	A pool with a garden of glowing mushrooms with stone-like caps (the area is blessed by a power of good fortune)
3	A wide gorge. There is a noisy waterfall (by a large statue)
4	A carved stairway leading to a tomb. (nearby is a sparkling stream)
5	A pool with a patch of decaying mold and a garden of moldy gourd-like fungal fruit. (someone has left an interesting rock)
6	A cave covered with inscriptions (close to an area of bioluminescent green moss)
7	A pale red-fruited "tree" (nearby is the fresh corpse of a giant bat)
8	A crystal walkway leading up a cliff and a wide hole (there is a cloud of blueish spores)
9	A clear pond and a patch of pulsating moss. (close by is a large fish-filled pool fed by a spring)
10	A tunnel-ridden cave with large stalagmite (close by is a bulky slab of obsidian)
11	A vertical shaft surrounded by moss (there are dark elf tracks less than a day old)
12	An area of fungal flowers. (there is a sweet odour in the air)
13	A set of stone steps leading up a cliff. There is a patch of spiky mushrooms covered in a tar-like substance (glowing beetles cover the area)
14	A deep ravine (there is an inscription here in Dwarven)
15	A pile of rocks by a patch of fiery-looking moss (near a stream flowing into a river)
16	A field of stones of varying sizes (there are several purple-cap mushrooms studded with large holes)
17	A shale walkway leading up a steep slope with a muddy stream fed by a spring (a partial collapse could easily happen)
18	A spring by a pool with a few twisted magic-feeding trees (it is touched by dark elf magic)
19	A glowing waterfall with a A forest of purple edible mushrooms (there is a strong air current here)
20	A wide chasm. There is a glowing crystal structure (which is associated with necromantic magic)

Underdark Semi-Civilised Locations

1d8+1d12	Underdark Semi-Civilised Locations
2	A crystal walkway to an inscribed stalactite. There is a garden of pink edible fungal (nearby is the fresh corpse of a giant)
3	A vaulted temple to a power of earth surrounded by quartz (there are troll tracks less than an hour old)
4	A stone bridge covered in phosphorescent edible mushrooms (colourful lights appear at random)
5	A portal by a deep hole. It is linked to the lower planes. (nearby is a recent collapse)
6	A flint quarry in a cave with large stalactites (close by is a ferry over a fish-filled river)
7	A mine shaft and a recently disturbed cairn. (there is a strong odour covering the area)
8	A set of ornate steps cut into a cliff-face carved with grotesque faces. (there is the corpse of a cloaker)
9	An area of rock-strewn ground with a small beast pen (a collapse could easily happen)
10	A strange carved hall with a garden of red edible fungal stalks (nearby is a patch of black edible puffball mushrooms)
11	A marble well in a patch of massive mushrooms with grain-like spores (fireflies are in the area, glowing yellowish-green)
12	A sheltered stalagmite house with a covered hole (there are bones of a goblin)
13	A shrine to a power of loss. (lying here is a backpack)
14	A burial chamber and three tall mushrooms (nearby is a strange portal)
15	An inscribed stone slab and an insect-covered shrine to a forgotten power (there is writing here in Terran)
16	An area of green stones. There is a pillar covered in runes. (there is a programmed illusion here)
17	A cursed area of creepy catacombs (there is a body on a spear marking a boundary)
18	A farm of dark edible puffball mushrooms (there is a cloud of greenish dust)
19	A strange crystal lattice and a newly-built shrine to a power of madness (the area is touched by the feywild)
20	A floating marble slab and a decorated tomb (close by are several sandstone columns)

Underdark Unusual Locations

1d8+1d12	Underdark Unusual Locations
2	A maze through a thick forest of fungi, mushrooms, oozes and insects. It is tended by an immortal minotaur who avoids fights.
3	Stalagmites and stalactites dominate a cave of many exits. Several are hollow and many bear carvings. Flumphs are attracted here.
4	The Mirror Above. An obsidian slab hangs from chains in an ancient carved hall. Periodically the slab shows images from the surface. Broken weapons and pieces of armor mark recent battles.
5	A noisy waterfall descends into a lake of clear water. On an island covered in glowing green mushrooms is a portal to the surface.
6	An air current flows into this high cave. Strands and ribbons of a white lichen float about. There is a shrine of travel hidden high up.
7	A canyon with walls glowing in patterns of green, blue and red. Light is from fungi, fireflies and decorations placed by a dark elf artisan.
8	The Forbidden Stairs. A long crystal stairway marked with statues of different underdark races. It is in the area of a forbiddance spell.
9	Bats infest this cave, their droppings covering an ancient obsidian arch. Water runs down it from an overflowing pool on a ledge above.
10	Several fetid pools contain various slimes and bubbling liquids. A highly intelligent roper hides among several large stalagmites.
11	The numerous beetles here live in symbiosis with several tall purple mushrooms. They are unaffected by the drifting poisonous spores.
12	Market Canyon. Staircases and many chambers are cut into this wide canyon. Merchants often trade here the protection of a beholder.
13	A fungal bridge crosses a trench of acidic sludge. Other bright fungi grow rampantly through connected caves, lit by a strange aura.
14	At the bottom of a wide pit rocks creak and shift. Occasionally geysers scatter stones and metal chunks through the area.
15	Rows of tended fungi grow in circles around a tentacled statue. It glimmers from magic it drains from the surrounding area.
16	Dread Falls. A waterfall plunges into treacherous rapids. Several altars of metal and crystal float in the waters. Fiends watch this place.
17	Magic courses through these crystal caves. Spells cast resonate loudly and attract psionic entities. The Astral plane overlaps here.
18	Wiry metallic vines span a dry gorge. Spider-like creatures spin them into mesmerizing patterns. Demonic symbols are marked in blood.
19	A bronze chain marks a ford through a sparkling river. Anything entering the river sparkles with dim light for 1d4 hours afterwards.
20	Outcast Citadel. A fort is built into several towering stalagmites. A crystal walkway runs around the edge of the surrounding cavern.

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