No, it's not a joke. Filmmakers Michael and Kate Garrett profile a pair of extreme unicyclists, who pedal their way through the nooks and fissures of underground caves. "It's just like a big underground playground," they explain. "That's why adding a unicycle really brings another level to it."

The Garretts are currently raising money for their next short film, Last Contact, a sci-fi thriller shot in the mountains of Bulgaria. If you'd like to donate—or if you enjoyed this video and want to see more of their work—visit their Kickstarter page.