At 4 a.m., we hopped in the tour van and headed to El Tatio, a geothermal field in the Andes mountains home to about 8% of all the geysers in the world. Just a few steps from the Bolivian border, more than 2.5 miles above sea level (4,320 meters), it’s the largest geyser field in the southern hemisphere. After a bumpy pre-dawn ride, we arrived to gray skies. The geysers rose and faded, from the earth to the sky. Some spouted, some steamed, some gurgled.