Jackson Blue Springs, Marianna Florida
by Ron Bear

3150 foot penetration at Jackson Blue. Weekend Report

Hi All,
We did two very interesting dives this weekend. The first was at Hole in the Wall. I am not going to detail this dive other than mention that the vis there is frequently not that good, but this weekend it was great. We spotted a side passage that we have been by six times without ever seeing it before.

Jackson Blue Sunday
Kim couldn’t go with on Sunday so John and I decided to do a maximum penetration. Generally we don’t bother to use nitrox while cave diving. There are several reasons for this. The main reason is really the cost. The second reason is that it doesn’t extend our penetration. This is because we always do decompression diving so lengthening NDL doesn’t mean longer bottom times it just means less decompression. The final reason is that the most convenient dive shop for our diving (Vortex Springs) doesn’t sell nitrox. For this dive I hit on a nitrox plan that I felt gave the most bang for our buck. The plan for this penetration (we actually were only shooting for 3000) already involved using two stage bottles. By filling the second bottle with EANX 32 and starting to breath that at 1400 feet of penetration we saved 24 minutes off of our deco. Filling the other three cylinders with 32 would have saved us another 18 minutes. We felt that the first four dollars (Nitrox costs us four dollars more than air) to save 24 minutes of deco was cost effective but an extra 12 dollars to save an extra 18 minutes wasn’t worth it.

This was our first time diving two stages so naturally there were some problems. The first problem was that when I attached the second stage bottle, I trapped the hose of the first stage bottle. I think that this was almost unavoidable with the reg tied to the first bottle the way it was. Prior to this dive I was cool as long as I tied the reg to the stage bottle. As I continue to dive two stages I will have to pay attention to WHERE I tie down my regulator.

The second problem happened about 240 feet into the cave. The entrance chamber at Jackson Blue is so big and roomy that I was not aware of what a cumbersome pig I had become by strapping on two stages. The entrance chamber continues another 60 feet but at 240 we leave that chamber by dropping over a cliff at the right side of the room. Access to that cliff is through a narrow crack. I have been through that crack sixty times with no problem. With two stages though I clanged my doubles into the ceiling and my stages into the floor. I moved over into a wider part and got through on my second try.

After going down the cliff the sand hill at the bottom of it slopes down to 95 FFW at a penetration of just over 300 feet. John had trouble at the bottom of this slope. At this point in the dive we were carrying roughly 30 pounds of gas (400 cubic feet). Because we were at 95 feet our wetsuits were compressed to the point where we had lost some 12 to 15 pounds of buoyancy. We were weighted to be neutral at 10 feet when down to 2 pounds of gas. This adds up to as much as 43 pounds negative and in spite of the fact that John has a 55-pound wing (Nominally 55), he couldn’t get neutral. There is a clay flat at the bottom of that sand slope that John certainly didn’t want to disturb. His solution was to push off of the bottom and go over the clay in a parabolic arc.

For the next 700 feet the bottom is solid rock. This is good pull and glide territory and John and I were really hauling. Both of us continually clanged our stages on the bottom there. By the way, I thought that the double stages would both ride on the left hip like a single stage. Actually the top one rode on the left hip but the second one more or less rode on the belly. The fact that we were hugging the bottom with a stage between our bellies and the floor made it pretty tough to not ding the stage along the floor.

Beyond 1000 feet at Jackson Blue the floor changes from rock to silt. We took the left fork at 1000. Although we had to get neutral there we did not have to abandon pull and glide travel. There are many big rocks there that are sticking off of the floor three to twelve feet.

At a penetration of about 1350 I was anticipating dropping my stages just beyond the coming fork. We had agreed ahead of the dive to drop our stages there regardless of what pressure remained in our first stage. This was because the deco charts I had printed out were based on 20 minutes of breathing EANX 32 at depth. Any farther into the cave and it would have changed our deco schedule. Because I was anticipating dropping the stages, I unclipped the butt of my top stage. There is a restriction just before that fork and I got stuck in it. I was really ticked off at myself for unclipping that stage. I figured that if I had it still clipped up tight to my body I wouldn’t have had so much trouble. I was too big to get through with the stages up next to me so I knocked the top one out away from my body. This made it so that I went through the 20-inch crack and that stage went through the 10-inch crack beside it. After the dive John told me that had been a great move. He had gotten to the restriction with both stages attached rock solid. He couldn’t get through so he unclipped the top one and did the same thing I did. I just find it amusing that I lucked into the right move while thinking I was screwing up the whole time.

From this point forward there is silt on the floor everywhere and hardly a rock shelf without silt spilling off of it. So from 1400 feet on it was a strictly swimming entry. If you want to wear 100 pounds of steel on your back and feel as graceful as a ballerina feels, then I can tell you how. Simply wear two Al 80 stages for 1400 feet and then take them off. It makes you feel great.

The next room in the cave is the Hall of the Mountain King. It starts at a penetration of about 1500 feet. This room is about 500 feet long. The ceiling in it is at a uniform 60 FFW but the floor varies from 95 to 65. The room has an average width of about 40 feet. I have spent quite a lot of time just floating around this room and not really going anywhere. Not for this dive though. John and I buzzed right through there trying to look at sights we had never seen before.

At the extreme north end of The Hall of the Mountain King, there are two “rabbit holes” on the west side of the passage. We had previously been through the far hole but not the near hole. The near hole lies at the bottom of the breakdown pile in the Hall. The passage there is not very wide and really nothing to write home about. It was a disaster as a short cut. Instead of going 100 feet at 70 FFW we went 200 feet at 95 FFW. This is the honest cynical truth. At the time neither of us saw it that way. After all this was the first new passage we had seen even though we had already traveled 2000 feet. I am always thrilled to be in new passage. I am sure that if it weren’t for the overwhelming amount of truly awesome stuff I saw later in the cave I would just go on and on about this passage.

The next room in this cave is the one that everyone at this cave is always talking about. It is commonly referred to as “The Trash Room”. Sheck Exley’s map refers to it as “Mystery Shaft”, but everyone is talking about the same thing. The mystery is that here is a shaft that brings garbage all the way from the surface but where is it? Most of the time I remove garbage from dive sites. This room will remain an exception. The cans and bottles all seem quite old so it is possible that the mystery shaft has caved in or become plugged. It is also possible that the trailer that the shaft sits behind is no longer inhabited by the breed of redneck that throws his trash in the woods instead of paying dump fees. At any rate, the trash is evidence of a connection to the surface (however small or tenuous) and it therefore delivers information to divers.

In addition to the info on the shaft, the garbage serves another purpose as well. This is the easiest room in the cave to use to reference any other room in the cave. Anyone who ever goes to the trash room knows that is where they went and they know how to tell other divers where they went.

Of course people aren’t excited about going to the trash room because of the trash. The room is some 200 feet long and most of the room has the same feeling of infinite width that you get by standing between parallel mirrors. You are in one passage, but you can see the line for another passage to your right. The white line reflects your light so you know there is a passage there. Low mounds of silt and the general inability of your light to shine that far hide the passage itself. The third name for the trash room is “Busch Paleontological Gardens”. There is some kind of fossilized critter scattered through about a 100-foot section of passage. The vertebrae are about 3 inches tall and wide. They have about a half-inch hole in the center. The ribs are about 14 inches long. The leg bones are nearly as thick as a full-grown cow but they are half the length of my forearm. Every rib looks about like every other rib and the same with the leg bones and vertebrae. For this reason it appears to be one skeleton as opposed to bits of multiple skeletons like at Fossil Cave. If you forced me to guess I’d say manatee. This is based on the legs being too short and squat to seem like actual legs. I freely admit that it is not an informed opinion.

We left the trash room and headed into territory we had never seen before. We had consulted the map prior to the dive to figure out where a 3000-foot penetration would place us. It is dumb to get off of the main line on the first trip, but the map did not show which path the main line takes. The cave is a twisty turny maze back there and I count 8 different places that would be a 3000-foot penetration. To be able to figure out where we had been after the fact I started recording azimuth of the main line and side passages. After the dive it literally took a few seconds to figure out which passages we had been in. It took a couple of minutes to figures out exactly how far we had gone down the last one however. One of the first things that John and I noticed beyond the elbow was a huge sea urchin fossil. My first impression was that it was the size of a football. Well I know how water makes things look bigger, so I went down and checked it out. It was fully six inches in diameter. If it had its spines it would be over a foot wide. I have never seen such a large sea urchin. A buddy of mine says he has seen them that big in California and Okinawa. Do they get that big in Florida now? (They obviously did THEN). It turned out that this big boy was not even that unique. We ran into a bunch more just like him as we traveled along. John stopped and showed me a bunch of little fossils that we have no idea about. They looked a lot like stick pretzels. I don’t have a clue.

The silt back there just rolled along like rolling hills. At one point John stopped and spot lighted a group that he felt looked just like a mountain range in the distance. I shrugged at him and I never did figure out what he was trying to show me. I really can’t figure out how John expected me to interpret a few waves of his light as, “Wow this looks just like a mountain range in the distance!”

Where we turned the dive the main line continued and there was a side passage going up. There is really only one side passage on the map that is on the line I was on (from the heading) and at the approximate penetration (based on time). This side passage is at 3150 feet.

One interesting fact popped out of analyzing the data after the dive. It took 30 minutes to swim from 1400 to 3150 upstream and only 18 minutes to swim back downstream the same distance. This is normal because of the flow. In the first 1400 feet the flow is stronger. Therefore I was really surprised to see that it had taken the same amount of time to swim downstream as it took to pull and claw our way upstream. How could the flow have had NO effect on our progress? The answer was to be found in our air consumption. I had used exactly twice as much air pulling upstream as swimming downstream and John had used 1.75 times as much. I really believe that if we can calm down and EASE our way upstream we can get farther on less gas.

DSAO
Ron

If you would like to contact Ron, email him at ronald.bear@eglin.af.mil