"With some training, a single operator can drill a thousand-foot-long tunnel, burrowing at any angle, in a matter of weeks. The most advanced [horizontal directional drilling machines] monitor your progress in real time while a self-feeding system automatically lays pipe," Jason Kersten wrote for GQ in early 2014. "The biggest industrial rigs can drill holes five feet in diameter, wide enough for a human."
A police officer, left, looks on as a television cameraman climb into a tunnel discovered by Mexican army, during a presentation to the media in Tijuana, Mexico, August 2, 2015.