英文關鍵字
catacomb
cave
caveing
cavern
cavity
cell
chamber
claustrophobia
claustrophobic
crypt
damp
dark
darkness
den
enclave
entrance
fear
formation
geologic
geology
grotto
habitat
hideout
hole
hollow
isolated
lair
location
mine
minerals
natural
openning
phobia
phobic
prehistoric
remote
rock
sanctum
scary
secret
shaft
shelter
small
speleology
stone
subterranean
tunnel
underground