One of the advantages of studying in Georgia (apart from access to the widest range of fried foods on the planet) is access to one of the world's great caving regions. There are hundreds of known, accessible limestone caverns through Alabama, Georgia, Tennessee, Kentucky, and the Carolinas all accessible from Athens, with a bit of planning and some spare time.
The University of Georgia Outdoor Recreation Department offers caving trips to introduce students safely to the sport of spelunking, and I grabbed that opportunity with both hands and never looked back. Luckily, my department, Discover Abroad, is also the part time home to Outdoor Recreation's only cave guide, Tom Carney. I've been on a good number of trips with Tom, both formal and informal, and will remain ever grateful to him for introducing me to the joys of getting dirty below the surface of the earth. I highly recommend it to the curious of mind, adventurous of spirit, and the dimensionally small.