In this region, the Wisconsin River once raged in white rapids between rocky banks rather than appearing as the serene scenes of today. Its riverbed and towering sandstone bluffs were formed more than 14,000 years ago when Glacial Lake Wisconsin broke through an ice dam and sent turbulent flood waters carving the landscape. Now tamed by 25 hydroelectric dams on its route from Upper Michigan to the Mississippi, the river is the longest and hardest working in the state. It has carried native people and explorers, supported commerce and leisure, and serves as the foremost ambassador greeting visitors to Wisconsin Dells.