abyss
alpinist
arch
big
broad
cave
cavern
cavers
cavity
climbers
crag
deep
descent
dismal
down
downhill
expedition
extensive
gloomy
grim
grotto
gulf
hall
hole
hollow
huge
journey
karst
large
light
mainsail
mountaineer
mountaineering
people
potholing
rock
sky
speleology
spelunking
stone
subterranean
tourism
tunnel
underground
vast
vault
wild
window