Cavern

d20	Cavern
1	Great mouth open to the sky
2	Rubble cone under a roof-fall
3	Vaulted hall, roof lost in the dark
4	Forest of columns
5	Underground lake shore
6	River gorge with a natural bridge
7	Terraced floor stepping down
8	Hall of fallen blocks the size of wagons
9	Balcony ledge over a drop
10	Mushroom-grown flat
11	Cathedral chamber with a single great pillar
12	Sinkhole shaft letting in a shaft of light
13	Mud flats that hold footprints
14	Waterfall chamber, loud with spray
15	Island in a flooded hall
16	Gallery of hanging stone spears
17	Wind-tunnel throat
18	Glittering mineral hall
19	Abyssal edge: a drop with no bottom in sight
20	The great deep, a hall too wide for any lantern

d12	Contents
1	Only the sound of dripping
2	A rotted boat pulled up on the shore
3	A rope bridge, half its planks gone
4	Lantern hooks driven into the rock
5	A cairn of piled stones
6	Blind white fish in the shallows
7	A survey party's abandoned camp
8	Giant fungus, some of it cut
9	A fallen climber's gear
10	Drums or bones arranged in a ring
11	A stone stair, cut by hands
12	A wrecked wagon, how it got here unclear

d8	Occupant	Build the encounter from
1	Empty: only echoes	—
2	Empty, though the mud holds tracks	—
3	A colony of cave vermin	Vermin
4	A territorial great beast	Magical Beast, Animal
5	Fungus that moves when unwatched	Plant
6	People who live down here	Humanoid
7	A thing of the deep water	Aberration, Ooze
8	A wyrm that sleeps on the heights	Dragon

d6	What is there
1	A sunken ruin older than the settlers
2	The great beast's roost
3	A lost expedition's last camp
4	A lake with something at the bottom
5	A hidden people's meeting ground
6	A road that leads further down than anyone has gone