The Perito Moreno Glacier is a major glacier located in the Los Glaciares National Park in the Santa Cruz Province of Argentina. It is one of the most significant ice fields in the world outside of the polar regions. The glacier is part of the Southern Patagonian Ice Field, the world's third-largest reserve of fresh water. It is notable for its dynamic behavior, characterized by a state of near-equilibrium where the rate of ice accumulation at its source is roughly equal to the rate of calving loss at its terminus into Lake Argentino. This stability is unusual among global glaciers, which are typically retreating due to climate change. The glacier periodically forms a natural ice dam that separates the two halves of Lake Argentino, leading to a dramatic rupture event when water pressure becomes too great. This cyclical phenomenon occurs at irregular intervals, sometimes several years apart. The glacier is a major tourist destination and is accessible via walkways that provide extensive views of its 5-kilometer-wide front, which has an average height of approximately 74 meters above the water's surface.