underground [Adjective] + cavern [Noun]

Strength Strength Dispersion
A:
17
CHISQ:
10,702.58
AWT:
7,603,201
TTEST:
4.12
G2:
199.46
FAWT:
7.15
MI:
9.3
LOGLOG:
38.02
JD:
0.71
MI3:
17.48
DICE:
2.56
RANGE: