Thursday 25th March 2004
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Sometimes a little fear is a good thing.
No matter how long I do this I love when I am put in a position where my psychology is challenged. Today was one of those days. I was back to diving today. Karl and I were tasked with going back to the Freeway line to investigate leads. Renee and Bob were to follow us in to do a video shoot together.
Karl and I made our way with five cylinders to the far reaches of the system. We dropped stages as we hit thirds. We reached a lead that he and I had investigated a few days ago. We tied off and made our way into a low room off of the side of the Freeway line around a large breakdown pile. The room is fairly large. It is in the shape of a donut with three passages off of it. The one we came in, another that leads back to the Freeway line and the third, a small lead. I had seen this lead days ago, but we did not have time to investigate it.
This section of the cave is deep enough to interact with the halocline. This room and lead are all below the halocline. When you work in the halocline visibility can be poor just by the mixing of the water. This room is no different. We swam into the passage dropping over the back of the breakdown pile. I was running the reel and Karl was following behind.
We investigated the passage leading out of the room to our left. It ran straight into the Freeway passage further in. We turned around and ran back toward the lead I saw the other day. Each time we changed direction I tied the line to make a station.
When we are exploring, we lay line to ensure our continuous guideline back to the surface, but to also to allow us to survey and map the new passage. When we lay line, we do not necessarily lay the line for easiest navigation. Each run of line, known as a shot, is made to try to go as long as possible in a straight line. Each shot is secured to the cave as tie into the cave itself or a placement. A placement is simply where the line makes a change in direction due to bending around an object. Every time the line makes a direction change that is known as a survey station. Once the line is laid, we traditionally survey it on the return trip out of the cave.
We also lay the line to avoid any line traps. A line trap is an area where a diver could not go if following the line in zero visibility or without lights. It is possible to lay line that under tension would pull into an area that would be impossible to swim.
We do not lay line in a cave unless we are going to survey it and produce a map. Leaving unsurveyed line in a cave is not exploration. It is sightseeing and littering. It is our policy that we will never leave line in any cave we explore unless we survey it.
When we survey we record depth at each station, the azimuth on a compass from the station to the next station and the distance from one station to the other. We also record sidewall and floor to ceiling distances and make comments on what we see. Surveys have varying degrees of detail. The type of survey we are conducting on this project is known as KLS, Knotted Line Survey. This means that we use line that is knotted every ten feet to estimate distances. Once the line is laid, we turn around and record our depth from the depth gauge, the azimuth from a compass and the sidewall data. All of this is recorded on a slate and comments are made. The distance is estimated to the first knot and knots are counted after that. The final knot to station distance in estimated and added to the rest of the distance. This is added to the slate.
From this limited information we are able to produce a fairly detailed map of the system. The team uses a program named Compass to electronically plot all the data collected. It is very easy to plot the data by hand as well. The use of the computer allows for quick changes and simple data correction. We correlate all of the data with GPS coordinates we record at each cenote and significant feature.
I worked my way back into the lead. It was very low but relatively wide bedding plane passage. Limestone is laid down in layers. The water dissolves the limestone taking the softest most easily dissolved material first. So, it is common to see passage in small cave that is narrow from ceiling to floor yet wide from side to side.
It is funny how over the years what I consider small has gotten smaller. Everybody who is an explorer is scared from time to time. I think a bit of mild apprehension is a good thing. It is part of what keeps you alive. It is when the apprehension becomes true fear that alarm bells begin to go off in your head. As Terrence likes to call them, the chattering monkeys are usually screaming. I had one of those moments today.
The bedding plane passage I was pushing into began to narrow. I kept seeing going passage. You have these moments of clarity where you find yourself talking to yourself. I looked into the lead and thought, well it is small but it looks like I can fit. For me that means still maintain neutral buoyancy, but have to make contact from time to time with the floor or ceiling as I push through. My big limiting factor is when I cannot see an area where I can turn around after a technical restriction or a long tight restriction that I would not feel comfortable backing out of or may be impossible to back out of.
What works on you more is that we were just so far away from home. It is different when you are only a few hundred feet away from home. But of course, getting stuck, really stuck sucks anytime. So, I am making my way through the lead. It begins to pinch off. I am talking to myself. “Okay you can still easily turn around.” Covered no go point number one. “Okay, it still goes.” No go point no matter what. I was making my way down the left side of the passage. I was keeping the reel with the line coming off close to the sidewall. In small cave, it is very important to run the line where you will not get caught up in it on your return trip out in what is often times zero to near zero visibility.
The situation gets more complicated than this. As you progress into new cave the silt that is trapped on the ceiling begins to rain down on you as your exhaled bubbles dislodge it. This makes life pretty uncomfortable for the dive buddy behind you. It also makes your decisions have to be made faster than normal as the silt will close in on you making seeing ahead very difficult.
So, as the passage comes in from the right, I keep going through my mental no goes list as I make slow progress forward. However, the no go list is doing battle with the “hey this thing still goes” list. You are reading the geology of the cave. The trend of the passage and the look of what is coming ahead. If I was above the halocline I could also be looking for water flow. Unfortunately, there is no flow below the halocline.
In this case the passage was getting smaller, but it was still going. It had a look that is hard to describe when I first looked at it. Some passages you can just tell are not going to do anything. Others you have a feeling about. A good chunk of this is an art, a feel, and impression or just a gut feeling. There is science too, but when the passage is small and the silt is raining down and you have only a few seconds to make a decision, it really comes down to just a gut feeling. So much goes into that, but you do what feels right at the moment.
But, then it happens. The chattering monkeys win the day. The passage got small enough where I could not fit any further without removing gear. I was faced with a choice of two restrictions and passage that appears to go on the other side. One restriction was low and wider, but I did not believe I could fit through it. The other was rounder, but looked like it might be possible. However, I would have to remove gear to do it. The no go list won.
There was a time where I would have felt fear pulse through my body at that moment. Having been in this same situation and few times before, now it is more of a controlled mental investigation. The conversation goes something like this.
“Okay, this is really small. You are over 4,000 feet/1,300 meters from home. The passage looks like it goes around the corner, but if it does not you have back out of a really tight technical restriction. Survey could be tough. Maybe I should just turn and survey what I have right now. It will be here again to push another time. Check your gas, okay got plenty. See what the silt does, not so bad. Well, maybe. No, it would be better to just turn. I can survey out and it will not be too bad getting back out from here.”
The situation was complicated by the fact that Karl was holding at the entrance of the small passage. He could not see and without any visibility it can feel like trying to make your way through Velcro. After a five minute debate, the decision was made I turned back. I had to survey the tie off backwards. I then turned around in the restriction to my right and completed the survey to the tie into the Freeway line. Once Karl saw I was okay, he began to collect water samples from five vertical levels in the cave. He began collecting at the ceiling progressing to the floor below the halocline. Amy had asked him to do that so she could compare these with the data she was finding at the surface of the cenotes.
After completing the tie in data from the Freeway line, we made our trek home. Resurveying the line that the new exploration line is tied into collects tie in data. This is important because we have to know where the new area ties into the Freeway line in order to map it.
We use an equipment configuration known as sidemount. We wear our cylinders on our sides with a specially modified BCD and harness. Everything is designed to be inline with your body. We wear all of our accessories on our back down by our rear end. This allows us to access much smaller cave than if we were to wear doubles on our back. Without sidemount, we would have never been able to do what we did today. Also, this configuration makes it much simpler to haul and move cylinders. It makes it easier to gear up in the water, plus you are more hydrodynamic.
Sidemount can also get you in trouble. Because we are able to access smaller cave it is also easier to get yourself in a place where you can get stuck or worse not be psychologically prepared for. It is extremely important that if you want to attempt to use this configuration that you receive proper training and work slowly over many dives before you put yourself in small passage. It is a slow evolution from what is considered small in back mount to what is small in sidemount. This evolution does not stop, the more comfort you develop in the cave and time in small passage the less scary it becomes. However, this does not diminish the level of concern or precaution you must take when attempting to push small passage. We still turn around when it does not feel right.
Two hours and forty minutes after entering Muchachos Karl and I surfaced. One of my favorite things about cave diving is where it takes you psychologically. It is the mental processes that you go through during a dive and especially when you are challenged in this environment that make this a very powerful experience. I am always surprised by where your mind will go during these dives. It is great, that is of course if you want to go there mentally.
The jungle team led by Amy made their rounds of all of the cenotes to complete water quality data. The students have been able to learn how to independently collect and collate all the data. They made quick work of it and were back at Muchachos when we surfaced.
The dry cave team led by Terrence completed survey of the entire line in the cave. Over the four-day period, the students have successfully completed the exploration and survey of the upper Aktun Chen system. They found a new opening to the system that no one knew about and learned a great deal in the process. The students conducted all of the survey. They will now produce a map of the system for the facility to use with its guests.
It has been a remarkable two weeks. Tomorrow we will take the students to see Nohoch Nah Chich. It is one of the most beautiful and white systems in the world. It used to be the world’s longest underwater cave system. Ox Bel Ha has since passed it, but this does not diminish the grandeur of the system. Sistema Camilo is amazing in its own right as well. Nohoch allows for a beautiful snorkel well back into the cavern zone.
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Links: Check out photos from the expedition here! | Read more on the expedition
