The Lost Sea is listed in the Guinness Book of World Records as the largest underground lake in the world. Located in Sweetwater, Tennessee about half way in between Chattanooga and Knoxville the Lost Sea was always calling those of us cave divers who lived nearby to go diving.
In 1974-1975 several cave divers were negotiating with the Chairman of the Board of Directors (BOD) of the Lost Sea to allow us to begin exploration of the underwater portion of the cave. Primarily Tom Mount was the “name” that gained us access to the Lost Sea. He along with Bill Schenck, a former NACD instructor convinced the BOD that we had the experience and ability to explore this system. The BOD was excited for us to do this because they too were curious where the cave lead to.
The Lost Sea is a world class tourist attraction with tours of the dry cave ending with a boat ride on the lake. Their web site can be seen at http://www.thelostsea.com. The underwater caves are simply an extension of the dry cave areas. The dry cave is extensive. We spent many weeks crawling around the dry cave and caverns getting a feel for how the system was laid out before we made our first dives. During the winter months while we were exploring we stayed overnight in an equipment room near the lake and had full access to the dry cave.
The walk into the cave, to the lake is about ¼ mile down an incline, there are no steps but carrying double 100’s up & down that incline for filling was a challenge. We had an old compressor on a trailer owned by Bill Schenck, of course it was powered by a gasoline engine and pumped about 8 cubic feet/minute. Some days Lost Sea staff hauled our tanks back and forth on an electric golf cart, other days we walked them up and down the hill.
During our initial preparations for exploring the cave we had surveyors to get into the dry cave and then onto boats and made a survey of the lake. The lake was measured to be 800 feet long by 220 feet wide, about 4.5 acres. Even before the surveys we knew there were potentially several passages that would lead off into “going cave” and our initial task was to determine where first to dive.
Part of the tour that tourists get is a glass bottom boat ride onto the lake. The lake was stocked with large Rainbow Trout and the perimeter of the lake was lined with underwater lighting. We used one of those boats to cruise around the lake and we did our initial surveys with wet suits and mask, fins & yes, snorkels. The water temperature was, as I recall very cold. Fifty-two degrees.
As chairman of the diving committee I was the record keeper, map keeper and point of contact with the BOD. All my records were in my parents home when it caught fire burning all my dive gear and all records & maps of our exploration, some years after the project ended.. I lived 45 minutes from the Lost Sea and had recently been certified as NACD instructor #28.
There were several of us who were diving over the almost 2 years that we worked in that system. There would be weekends that we dived all day & night and then weeks when none of us could make it up there to dive. We required all divers to be NACD certified divers. The NSS-CDS was yet to be formed. NACD at that time had only 1 level of certification, Cave Diver.
Some of the divers that assisted were Jim Fishback, Victor Sparks, Sheck Exley, Mac Fair, Jeff Davis, Billy Young, and Tom Mount. Tom got us in the door and made a few dives with us doing the initial surveys into the underwater cave system & really got us on track exploring the main passage. Tom was at that time the training director for the NACD and his help was key. Tom lived in Miami at the time and found the 20 hour drive prohibitive to be with us every weekend that we dived. Sheck talks briefly about the Lost Sea in “Caverns Measureless to Man”, but was not able to make that long drive from North Florida very often.
We had no way of knowing what depths we would encounter , but we all suspected that the depths would be in excess of 100 feet very shortly after beginning the exploration, we were correct. The underwater section of the cave angled down just as sharply as the dry cave did. We were diving air, and decompressing on air. That was all we had in those days. The hi-tech gear we had included a Benjamin valve (Dual Outlet) , harnesses attached to our tanks and a horsecollar BCD with optional power inflator. Victor Sparks elected to use oral inflation, rather than the power inflation option. Our lights were Frank Martz type lights with wet NiCad batteries & sealed beam halogen 100 watt bulbs. We got an hour burn time out of these lights. Our reels were of a Frank Martz design also. All of my reels & lights were built by Bill Schenck who never dived with us after all the work of getting access due to personal reasons not to do with cave diving.
Our primary tie off was in open water, we tied to one of the underwater lights dangling down about 10 feet under the surface. The secondary tie off was quite another problem, as was all other tie offs. We discovered immediately that all outcroppings from the wall and ceiling were very delicate and any attempt to tie line to these outcroppings resulted in destruction of the out cropping and a corresponding decrease in visibility.
The bottom was very thick with very fine red clay silt. It was in some places 6 feet thick and others as much as 2-3 feet thick. No where that we ever found had a rocky bottom. We resolved the no tie off point issue with stakes we would drive into the silt. This silt was almost like jello, in that it wiggled when you got near it
These stakes we made out of reinforcing bar with a fender washer welded onto the top. Mac Fair volunteered to make up a batch of these stakes before our next series of dives. On our first set of dives we installed no line because of this.
Our next trip up, armed with our exploratory reels and homemade tie off points we attempted to install exploratory line into the system. Mac fair made these stakes for us before every trip up to dive. We decided on 3 man teams for line installation because the weight of the stakes was so much that is was too much for 1 diver to carry while one diver was laying line. One diver ran a reel, and both other divers would carry 1 or 2 of these stakes.
We installed a lot of line that next weekend. The stakes worked fine, they were all 6 feet long and most of them went into the silt to a point where only a foot to 18 inches stuck out. The diver placing the stake had to be extremely careful and be slow in placing the stake so as not to completely blow out the 15 feet of visibility we had most of the time, on the way in.
Jim Fishback was employed by the U.S. Geological Survey during the time we were doing this exploration. One weekend he brought with him an underwater sonar unit so we could measure dimensions of the rooms we were swimming through. Most of the time we were unable to get any sense of the size of the underwater rooms due to the limited visibility as well as the enormous size of the rooms and the cave.
This unit was a flashing type fish finder in a waterproof housing. It would read as deep as 120 feet if it were mounted on a boat. We took this unit with us on dives after we had installed line and were attempting to make an initial map of the cave. The unit maxed out at 120 feet in the first room we came to after the lake, we were along one wall, but the room was so large that we could not get a reading on the opposing wall, or the end of the room. The room was at a point of about 400 feet of penetration, and 110-120 feet of depth. It had taken us several dives to install 400 feet of line.
We decided to continue installing line as we had leveled off at 110-120 feet and the cave was going. One dive I recall coming to the end of my reel, after having installed about 300 feet of line, we drove a stake into the silt and I tied off the end of the line to the fender washer. We blew the vis out to zero, and as I was cutting the line and stowing my empty reel I realized I was off of the line, I had no safety reel. I knew I was in deep trouble if I did not relocate that line soon. There was no way to wait out that clay silt, there was no visibility and I would not expect my buddy to be able to find me, he had no safety reel either. Safety reels were introduced to cave divers after this event took place and we were not trained to use them, or even knew of their existence. Obviously I found the line after a minute or two (seemed like 20). Using the methodical, non-line search I had been taught in my 6 month long full cave course.
We found anthodites or cave flowers at 65 feet deep on the walls, this was fascinating to the geologists and other science guys because we know that these cave flowers cannot form underwater. These flowers were photographed, copies sent to the BOD, and others burned in the house fire that also took my high school annuals and other memorabilia of my 20 years on earth.
We installed one continuous guideline with no off shooting lines because the passage kept going .Overall we installed about 1500 feet of line in that system.
The one event that continually occurred made us all think long and hard about continuing this exploration was the percolation that we experienced on every dive. Since no human had ever been in there before us, the overhead had clinging to it all the silt of a thousand years or more, and every time we exhaled stuff rained down on top of us. Mostly it was clouds of silt, occasionally a few small rocks would fall.
During every exit we experienced 5 feet or so of visibility due to this percolation, couple that with 100-120 feet of depth on air, Fifty two degree water and it created an added stress factor for us all.
One dive with Tom Mount as team leader, and Victor Sparks as team member an event took place that made us re-evaluate the safety of the project. Tom and Victor described a large boulder falling from the ceiling and almost hitting them. As I recall, they stated that the rock, the size of a Volkswagen beetle could have pinned them to the bottom with little hope of escape. The chairman of the BOD asked for my word, early on in our exploration that I would shut the project down should we find conditions that we felt were more risky than we should accept as a risk factor.
It was decided by many of us, after this incident that things on the ceiling were loosening up because of our bubbles. More and more rocks and debris were falling down on us on every dive. We knew we had explored about 1500 feet of passage, created a map and discovered significant water table changes. We saw changes in the geology with the depth and were able to relate those changes to various geologists who learned from it. We did not know where the cave ended up, we never walled it out.
Because we were diving and decompressing on air we were spending long hours in that frigid water. The dives were getting longer and longer with each push and the deco was getting colder and colder.
Most of us felt we had reached our limits and I notified the chairman of the BOD, provided them with maps and a few photographs and ended the project with no fatalities. There was a couple in our group who felt we should continue pushing the cave and we will never know if we called it off too soon. I sleep well at night making the decision to stop.
As far as the future for further exploration of the Lost Sea there is great potential for Closed Circuit rebreather explorers, with dry suits and modern deco gasses. I think the property was sold to a group of attorneys who have expressed reluctance for further exploration due to liability issues. I have been contacted a couple of times by divers seeking advice on how to get back in there. So far no one has seriously followed up on it.
We only explored one passage off of the lake, it kept going and going and we saw no need to look for other passages. My guess is that there are many more passages waiting to be explored.