Perito Moreno advances three meters per day while most Patagonian glaciers retreat, pushing its 60-meter-high terminus into Lago Argentino with enough force to trigger house-sized calvings every few hours. The glacier's anomalous growth stems from a steep accumulation basin in the Southern Patagonian Ice Field, where annual snowfall exceeds ablation rates despite regional warming trends documented since the 1990s. Francisco Moreno never saw the glacier named for him in 1899; the Argentine explorer died in Buenos Aires two decades after mapping the disputed frontier that would place this ice mass 17 kilometers inside Argentina's Los Glaciares National Park, accessible only by crossing from Chilean Patagonia. Puerto Natales became the improbable staging ground for these cross-border excursions after the 1994 paving of Ruta 40 reduced the El Calafate approach from six hours of gravel washboard to three hours of asphalt. The 340-kilometer route crosses the Cerro Castillo border post at 518 meters elevation, descends through the basalt plateaus of Santa Cruz Province, and terminates at the Magallanes Peninsula walkway system—4.5 kilometers of steel catwalks cantilevered above Brazo Rico. Park infrastructure expanded in 2001 with the addition of southern viewpoints overlooking the glacier's contact with the peninsula, where cyclical damming of Brazo Rico creates pressure differentials that rupture the ice bridge every four to five years. The 2020 rupture drew 3,500 spectators; the phenomenon recurs when meltwater accumulation behind the glacier exceeds 30 meters of hydraulic head. The conservation fee of 50,000 Argentine pesos—indexed quarterly to match inflation rates that reached 211 percent in 2023—funds ranger patrols across the park's 726,927 hectares and maintains the walkway network that handles 600,000 annual visitors. Morning access between 08:00 and 10:00 precedes the arrival of El Calafate tour buses, which concentrate foot traffic between 11:30 and 14:00 on the lower terraces. The glacier's orientation—facing northeast into prevailing westerlies—creates optimal lighting for photography from mid-morning through early afternoon, when solar angle illuminates the serrated pressure ridges and crevasse fields that define the terminal face. Blue ice visible in calving events dates from snowfall compressed over 200 to 300 years, its color resulting from air-bubble elimination and selective light absorption at wavelengths above 600 nanometers. Glaciologists monitor the terminus with time-lapse cameras and GPS arrays; current data confirm advance rates averaging 1.2 meters daily at the central axis.