Huilo-Huilo (Spanish pronunciation: [ˈwilo ˈwilo] audio (help·info), Pronounced: WEEL-oh-WEEL-oh) is a waterfall located in Huilo-Huilo Biological Reserve in southern Chile. It lies next to Neltume in the international road to Hua Hum Pass, in the border to Argentina. The waters of the Huilo-Huilo Falls originates in Lácar Lake in Argentina. During the summer it frequently dries, as consequence of low precipitation and subterranean runoff. As consequence of this infiltration a large aquifer is situated under Mocho-Choshuenco volcano. Contact between the water of the aquifer and magma may have caused the explosive phreatic eruptions that created the Tumba del Buey (bull's tomb) crater on the western flank of the Mocho-Choshuenco.
Coordinates: 39°51′12″S 71°57′16″W / 39.85333°S 71.95444°W