What made this mine extraordinary is also what made it terrible. The coal seams of Lota dipped down from the coastal cliffs and ran out under the seabed, so the work followed them offshore, deeper and farther from daylight with every passing year. Miners labored in the room-and-pillar method, often on their knees in low galleries, hauling coal in the dark while the weight of the Pacific pressed down somewhere above. There were no elevators carrying these men to their shift in comfort. They went down on their own feet, into heat and dust and the ever-present threat of firedamp, and they came back up the same way, if they came back up at all.

Baldomero Lillo was born in Lota on January 6, 1867, into the world of the coal basin. He worked as a clerk in a company store, which put him shoulder to shoulder with the miners and their families, and he went down into the pits himself. What he saw never left him. In 1904 he published Sub Terra, a collection of stories drawn directly from the lives he had witnessed, and one of them carried the mine's own name, El Chiflón del Diablo. Lillo did not write the miners as heroes or as scenery. He wrote them as men, with families waiting at home and a company that counted their lives cheaply, and his work helped a whole country see what its coal had cost.

It is easy, standing at a mine that is now a tourist site, to turn the danger into a thrill. The harder and truer thing is to remember the people. The miners of Lota were not characters in a ghost story. They were fathers and sons and neighbors who chose this work because the coal basin offered little else, who organized into some of Chile's earliest labor unions precisely because the danger was so real, and who buried their dead with grim regularity. When a collapse or an explosion came, the loss rippled out through tight-knit families and a town that knew every face. Lillo understood this, and any honest visit to the Chiflón has to begin there, with the human cost rather than the spectacle of the deep.

The mine worked until 1970, and on October 6, 2009, it was declared a National Monument of Chile in the category of historical monument. Today guides, some of them former miners or the children of miners, lead visitors down the same passages, helmet lamps cutting the same blackness, into a museum that is also a memorial. To walk these galleries is to feel, however briefly and safely, the cold and the cramped dark that generations endured for a wage. The mine has gone quiet, but it keeps a promise the rest of Lota has tried to keep too, that the men who went under the sea will not be forgotten.