Ten meters in, they are able to stand up. Here, the drift has the same vaulted shape, but it’s six feet high and six wide, buttressed by reinforced-concrete arches that they have poured in wooden forms on the floor. The iron rails run far away into blackness. A train of three mine cars sits on them—sheet metal boxes filled with shattered basalt. "We remove waste by hand tramming," Goto Dengo explains. "This drift, and the rails, are perfectly level, to keep the cars from running out of control."