This state park was once an amusement park – glass-bottomed boats were invented here in 1878 to show visitors the natural springs and stunningly clear waters of the Silver River. Although the amusement side of things closed in 2013, the natural beauty and the boat tours (adult/child $11/10) over Mammoth Spring remain. The spring is the world's largest artesian limestone spring, gushing 550 million gallons of 99.8%-pure spring water per day.