speleologist

noun

1. A person who studies or explores caves or studies the science of speleology.

   “The first man known to have descended Gaping Gill is well known on the Continent as an expert cave-explorer or speleologist — to use the new term which he perhaps invented.”

   “The biography of Robert de joly, a famous French speleologist who spent his life exploring caves, revealed an experience in which he stumbled into some cave areas high in carbon dioxide (CO₂) and developed a severe headache lasting twenty-four hours.”