What does a spelunker do as a hobby?

Answer 1

Spelunking is a hobby. It is the amateur ( as opposed to professional or scientific) exploration of caves. It is not generally related to prospecting for minerals or construction sites such as projected tunnels- as would be professional geology. Speleology is the scientific study of caves. a spelunker is to a speleologist as say, an amateur Scuba diver is to an oceanographer.

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"Spelunker / ~ing" is now entirely slang. It was concocted in good faith by a couple of American cavers in the 1930s or 40s, but never caught on anywhere else, became corrupted in its own country to denigrate novices and dilettantes; and no longer appears in any serious caving literature including that from America. The normal, international, English-language words are "cave", "caving" and caver".

Also an enormous amount of speleological study is carried by amateur cavers as a development of their hobby. The professional speleologists are so by reversal - they are geologists, biologists, etc by trade and training but their hobby is caving so they combine the two.

After all you cannot study a cave unless you are a caver!

Incidentally, amateur divers correspondingly contribute a lot of valuable, serious knowledge in marine Biology and Archaeology. The boundaries between amateur and professional in the natural sciences are by no means clear cut!