Triple Divide Peak, an 8,025-foot mountain in Glacier National Park’s Lewis Range, is a rare hydrological apex where the Continental Divide meets the Northern Divide. From this single summit, water can drain toward three ocean basins: the Pacific by way of Pacific Creek and the Columbia system, Hudson Bay through Saint Mary Lake and the Saskatchewan-Nelson system, and the Gulf of Mexico through Atlantic Creek, the Missouri, and the Mississippi. This makes the peak an unusually clear illustration of North America’s converging drainage systems. It also stands within the Lewis Overthrust, where ancient Precambrian rock was thrust over younger Cretaceous layers millions of years ago.