This is an interesting and unique spring to say the least. The spring is actually under the main section of the Suwannee. Since the Suwannee is filled with tannic acid, the clear water emanating from the spring isn't immediately visible. In fact, while I'm fairly sure the spring is under the middle of the river, the spring water is forced to the bank on the east side (due to the temperature difference). Check out the pictures below to get a better idea of what I mean. This creates the opportunity to see the strange mixture of crystal clear and tannic water that is constantly changing.
The temperature difference is also fascinating. Just wading from the shore let's you take steps from warm water into icy water and back. I don't think swimming was intended at this spring but it was remote and inviting enough to give it a go.
I took a few movies of the descent to the spring mouth but I was never able to reach it completely; the visibility drops off linearly as the river water becomes more of the mixture. It's actually very creepy; the clear and chilled water is quickly replaced with increasingly darker and warmer water. It's enough to make you turn back simply from the sensation.
The banks are covered in limestone formations and rocks as is typical of the upper-Suwannee springs. It's somewhat difficult to position yourself for good photos as the only way to travel down the beach is over said rocks. Also, as motorized watercraft travels down the river, the waves disturb the visibility and mixture of the spring heavily.
This spring isn't much fun, but it's quite unique, well-marked from the road, and less than five minutes from the interstate, so I would recommend a quick trip to see it.
I expected something rank when I looked at the satellite view; it was dark, heavily wooded, and with a name like "foul mouth", it wasn't looking good. However, I'd be lying if I said this wasn't my favorite memory from the entire trip. We parked at the top of the landing and scaled down the boardwalk to the karst window (http://en.wikipedia.org/wiki/Karst_fenster).
This spring is one of those "sum of its parts" locations that just feels so nice regardless of its individual values. The water visibility was pretty bad. I took a few snapshots of the rise but it was nothing but a solid slightly-tannic scene. It's also in a small ravine, so the sun doesn't reach much and the canopy is thick. It's also a fair bit creepy. The spring water emerges from a dark shaded area; I tried to swim into it but I lost my appetite for adventure fairly quickly. About 200ft down the run the water abruptly enters another cave, and given the speed of the water, I didn't want to get anywhere near the hidden sinkhole.
Despite all that, it was very quiet and pristine. The transparent water gurgled down through the rocks and fallen branches in such a way that the normal soothing sound resonated throughout the area. The run was a perfect depth - about 2.5' - to allow wading or swimming. The water as always was icy cold, but the tree cover made it just a little cooler. After I'd been taking pictures from the run for about 10 minutes, the sun slid behind some clouds and the area became very chilled, almost like an AC unit kicked on. Mist/fog started to rise off of the run and within minutes, the sun came back and started lancing through the fog to create some of the most sickening sweet imagery I'd ever seen at a spring. My camera didn't do it justice (especially since the lenses kept fogging up). I ran down the bank to get shots of the sink and the trees in this state.
I wanted to stay and just bask in the privacy and peacefulness of the spring, but I had too many more to see on this trip. I don't know if I could go back with the same expectations, but I do hope I can chill in the run for an hour or so one day.
I thought it would be larger from the pictures I'd seen, but it was still a nice sight. The walls are rigid and carved and the spring looks other-worldly. I'm sure I could have taken a dip into the spring but I was afraid I might damage the rock cutouts. I lied; it looks really creepy in-person. The water flows out a small opening the in wall into the Suwannee River, but it's very difficult to get down to that area. I jumped out one of the "windows" and promptly discovered the 6-foot drop to the sand bank below.
The smell of sulfur is strong from the outpouring of water and the characteristic white bacteria/algae/whatever was all over the plant life surrounding the outlet. I walked around the area a bit, finding some other smaller seeps coming from under tree roots. The river has long outstretched banks in this area allowing you to walk out and grab some nice pictures. I walked all the way to the eastern bend in the river and found a set of concrete stairs leading back to the parking lot; good thing too, because the dock leading down to the bank stops about six feet from the ground.
It's a very cool sight-seeing spring, but don't expect to do much else. There's also an abandoned bridge not too far up the road which is worth seeing (see the pictures below).
It's a sinkhole. I mean, I guess I wasn't expecting tannic water coming from the "spring" itself. The area was pristine and very close to the nearby interstate exit. If you're in the area, it's worth the short drive down just to check it off your list, but not much else.