Scorpio and Cavern Worlds
On Page 136 of Dr. B. V. Raman's Hindu Predictive Astrology, India's most celebrated astrologer of the 20th century has made a few spontaneous comments on the cavern worlds below. Specifically, he relates them to the sign Scorpio.
"... natural crevices, dark retreats, caves, openings in the Earth, dens, kitchens, vaults, ... underground cells or constructions, ... molehills, places abounded by serpents, vermin and reptiles, wilderness containing ant hills, ...)
Truly, the bowels of the Earth are represented by Scorpio.
Cheers!