Giant Springs State Park 
4803 Giant Springs Rd
Great Falls, MT 59405
406-454-5840
http://stateparks.mt.gov/giant-springs/
State Park: Birding, Fish, Hike, Picnic, Walk, Water Sports
Set aside a whole afternoon at this historic freshwater springs site, discovered by the Lewis and Clark Expedition in 1805 and one of the largest freshwater springs in the world, flowing at a measured 338 million gallons of water per day!