A forum member tipped me off about an abandoned railroad tunnel near Holiday Island, Arkansas. I knew there was an abandoned railroad down there, but I'd never heard about the tunnel. I looked the place up on the internet, put the coordinates into my GPS, and headed down to Arkansas. I found it without too much trouble, but it would've been nearly impossible without the GPS because this place was out in the middle of nowhere. The tunnel turned out to be amazing, and since it was full of water inside, I even got to try out my new waders.