"Caving" is simply the informal name for what cave explorers ("cavers") do, investigating and exploring and traveling through caves of all kinds. A more formal name for it is "speleology." Caving of any kind is a difficult activity and not for everyone; certain kinds of caving, such as cave-diving (exploring underwater caves using scuba gear) are among the most dangerous adventures in the world. I went caving once when I was in college. It wasn't a very difficult cave to get through, but it was still quite an experience, and nothing like the well-lit tourist-attraction caves I'd been in before. Ever since, I've been interested in caves and caving. At the moment I have these books on the subject:
THE ADVENTURE OF CAVING: A Practical Guide for Advanced
and Beginning Cavers
McClurg, David
c.1986, D&J Press
ISBN: 0-937757-00-4
This is pretty much what the title says: a guide to caving.
BEYOND MAMMOTH CAVE: A Tale of Obsession in the World's Longest Cave
James Borden & Roger Brucker
c.2000, Southern Illinois Univ Pr
ISBN: 0-8093-2346-X
The well-named Mammoth Cave is the best-known segment of an enormous, complex system of caves that exists below the Flint Ridge region of north-central Kentucky. Today, the Mammoth Cave/Flint Ridge cave system is known as the longest continuous cave system in the world, with more than 300 miles of mapped passages. But it wasn't always so. From 1972 to 1983, two competing groups of cavers sought to outdo each other in the amount of cave they mapped, and to find the long-sought connection that would link Flint Ridge to Mammoth Cave. James Borden and Roger Brucker were both part of that work. This is their first-person account of these "cave wars". It also serves as a sequel and update to THE LONGEST CAVE, which Brucker wrote with Richard Watson several years earlier.
CAVE PASSAGES: ROAMING THE UNDERGROUND WILDERNESS
Taylor, Michael Ray
c.1996, Vintage Books
ISBN: 0-679-78125-0
A sort of general book on caving, including a number of firsthand accounts of different cave explorations.
THE CAVES BEYOND: The story of the Floyd Collins' Crystal Cave exploration
Lawrence and Brucker
c.1975, Zephyrus Press
ISBN: 0-914264-18-4
Floyd Collins was a famous caver in the early 20th century who spent much of his time exploring Crystal Cave, a cave complex in the Mammoth Cave region. In 1954, the National Speleological Society sent a major expedition into Crystal Cave. This is the official report on that expedition.
THE JEWEL CAVE ADVENTURE: FIFTY MILES OF DISCOVERY UNDER SOUTH DAKOTA
Conn, Herb and Jan
c.1977, Zephyrus Press
ISBN: 0-914264-20-6
Jewel Cave is a large underground cave complex located in the Black Hills of South Dakota. In the 1950s it was thought to be only a small cave, until Herb and Jan Conn started exploring it. When this book was written, they'd been exploring Crystal Cave for over twenty years and had mapped more than fifty miles of passages in a complex three-dimensional maze.
THE LONGEST CAVE
Brucker and Watson
c.1976, Southern Illinois Univ.
ISBN: 0-8093-1322-7
This is the forerunner or prequel to BEYOND MAMMOTH CAVE (see above). Mammoth Cave in north-central Kentucky is famous as a tourist attraction. But the tour area is only a tiny fragment of the whole cave system. The whole complex is known as the Mammoth Cave/Flint Ridge cave system, because much of it lies beneath neighboring Flint Ridge. The Flint Ridge/Mammoth Cave complex is (or was, in 1976) the largest known cave complex in the world, with more than a hundred and forty miles of mapped passages. This book is the story of the exploration of the Mammoth Cave/Flint Ridge system, including the climactic expedition that finally connected Flint Ridge to Mammoth and proved they were one vast cave system.
PLANET EARTH: UNDERGROUND WORLDS*
Jackson, Donald Dale
c.1982, Time-Life Books
ISBN: 0-8094-4320-1
A look at cave systems throughout the world, including the Mammoth/Flint Ridge system which is the largest known, and a Borneo cave that contains the largest underground chamber ever found.
SPELEOLOGY: THE STUDY OF CAVES*
Moore & Sullivan
c.1978, Zephyrus
ISBN: 0-914264-22-2
A more technical survey of caves, caving, and the study of caves and their inhabitants. Published by the National Speleology Society as a general introduction to the geology, biology, ecology, and archaeology of caves.