This is very cool. I have been there many times and that’s the area where I grew up; that river is probably the place I know the best in the world.* The information below the video is a bit inaccurate, unfortunately.

The Santa Fe River is not always dark. It’s tannin-stained certain times of the year and under certain conditions. Generally, the water is coffee-dark in the winter and spring, while in the summer (depending on rain) it is primarily spring-fed and becomes quite clear. I have seen it become crystal-clear enough that I could see easily to the bottom of 30 foot deep spots in the river, just like looking through a window.

The tannic acid also comes from oak leaves, not just cypress.

Another slightly misleading part is the info about the spring. There is no spring actually called “Devil’s Spring” at that location. The entire three-spring system is called the “Devil’s Spring System.” That system comprises three springs: Little Devil, Devil’s Eye and Devil’s Ear. The park itself is called “Ginnie Springs” and it is privately owned, though it should be a state park.

The diver is most likely in Devil’s Ear, which is right on the Santa Fe.

I have swum in all three springs and in just about every spring on or near that river at one time or other.

*My partner was looking at photos of the Santa Fe with me one time and was marveling that I could identify where on the Santa Fe a photo was taken by the arrangement of trees and rocks. Those, though, were my navigation points for fishing and estimating my boating time.