Tight and open
These passages join chambers the main tunnels do not, and the cave's dwellers do not use them. They alternate between a squeeze you slip through and an open gallery, and no two run alike: a round tube, a tall narrow canyon, a leaning rift or a low, wide crawl.
Things in the way
Now and then a passage holds one obstacle. A ledge is a climb up or a drop down. A chasm cuts across the floor: jump it, or take the shelf along one wall, and if you fall short, the bottom climbs back out. A pit is crossed on a narrow stone bridge, a fin of rock or a ledge round its wall. A choke is a plug of rock with a gap to peek through: dig it open with a hammer.
What is at the end
A gallery past an obstacle may hold a satchel left by a raider, or a few everyday goods. See Caves and Climbing.