spelunker

Spelunker sounds like the noise a pebble makes when you drop it down a deep hole and into dark, hidden water far below. But there's nothing dark or obscure about the etymology of the term. We borrowed "spelunker" from Latin spelunca, which in turn derives from Greek spelynx. When you get to the bottom of things, you find that both the Latin and Greek words mean "cave." Although "spelunker" might sound neat, be careful: some cave-exploring enthusiasts prefer the term "caver."