Brown and blue blend as water from Ginnie Spring mixes with river water tinted by plant tannins. While this natural dye is harmless, man-made pollution clouds the future of these fountains—a fact Floridians must now confront.

Florida's 320 natural springs gush out over eight billion gallons of drinkable water every day. How these springs work, where the water comes from, and the ways in which they are all connected remain mysterious, but scientists and underwater explorers are working to change that.

(Text adapted from and photograph shot on assignment for, but not published in, "Unlocking the Labyrinth of North Florida Springs," March 1999, National Geographic magazine)