A few buddies and I rented a Pontoon Boat from Cave Adventures in Marianna and headed to a couple of cave systems on the Mill Pond last weekend. First we hit Hole in the Wall, which is just that, a hole int he cliff. The cavern is about 20ft deep, then turns into a 4ft high restriction which then opens up into a 40ft deep pit. After heading down that, you are at 80ft,about 200ft back, and can choose to go upstream or downstream. We chose upstream, but the visibility quickly dropped to 5ft , so we turned after 100ft, and tried downstream with our remaining air. Visibility was better there, but as one of our buddies was on double 80s, and I was using tables for bottom time, our dive was limited. We only did 100ft that way. BAck on the boat, we suffered through the freezing wind, and hurridely got out of our wetsuits.
Next we topped off our tanks, and then headed up the pond to twin caves, so named because two entrances lead into the cavern. We put back on our now frozen wetsuits, and headed in. Like hole in the wall, Twin Caves is a shallow entrance weith lots of silt, which makes it hard to get in without messing up visibility. But the cavern stays clear. After tying into the mainline, we head down a short pit to 45ft, and then into the Subway, which is essentialy a 1000ft straight tunnel about 15ft high and 10ft wide. After 20 mins of that you hit a T in the line which heads down into a fissure or straight to eventually loop back up the fissure. That was a good turn point, so we headed out. Luckily it had warmed up, so changing wasnt as bad. All in all it was a great day of diving.
I took a bunch of land pics which can be found here - http://northfloridadiver.net/media/pics/millpond206/millpond206.htm
And more info on the millpond can be found here - http://northfloridadiver.net/sites/jb.htm