Shadowing Steffi in
Blue Holes
John Bantin joins diving scientist Steffi Shwabe on her rounds of the experiments she has set up in the flooded inland caves of the Bahamas.
STEFFI Schwabe strode ahead of me through the swampland, shrugging off attacks by aggressive insects as easily as she carried her two steel cylinders, swinging from her hips. It was mid-summer and the Bahamas were enjoying particularly hot and humid weather.
I followed pathetically behind, a deafening pulse in my head and sweat stinging my eyes.
"Blue Holes are the entrances into some of the world's most spectacular cave systems," she told me. "These openings can be found among the shallow creeks, inland lakes, and shallow banks of the Bahamas."
For many years, popular ideas about the origin of Blue Holes have been mixed with local superstition and myth. Cenote-type caves can be found both inland and in a marine setting.
Water movement is generally restricted in these systems and in many instances several distinct thermoclines, haloclines and chemoclines can be found within the water column. The Lucayan caverns are part of the most extensive cave system known to exist in the Bahamas, with more than 10km of mapped passages.
There are three known dry and two wet entrances to the system. The latter discharge into a mangrove creek, and the main dry entrance is known as Ben's Cave, named after Ben Rose, a long time instructor (now retired) at the Underwater Explorers Society in Freeport, who first explored these caves.
During my visit with Steffi, Ben's Cave was closed to protect the vast number of bats that were roosting there. These bats provide an important source of nutrients to the waters in the form of guano, while feeding the mangrove snapper with the occasional baby bat that falls into the water.
Steffi took me to the Lucayan Burial Mound entrance - named after an Indian burial mound found at the site - which was also home to plenty of roosting bats. I considered them important allies in my war against the constant swarm of mosquitoes and horse flies that attacked me as I came from the carpark - I didn't care that my equipment had to be put down on a surface of thick bat excrement.
"I really enjoy taking people into these caves, to share what I experience so often. I like to see their reactions," Steffi enthused.
After the exhausting walk, carrying my camera gear and diving equipment through the undergrowth to the cave, it was a relief to get into the cool of the open cave and have a swim in the fresh-water pool. Kitted out with adequate air supplies and lights, we dropped down through the pool to 14m where a sign indicated that it was prohibited to enter the cave.
Steffi had special permission because she was doing research, and I was allowed to accompany her to take some photographs.
Steffi intended to install an experiment involving an extremely sensitive multi-level current indicator composed of a series of lightweight vanes suspended on a line.
We entered the flooded outer chamber, which was enormous - about the size of a small church. This part of the cavern was about 10m deep, except for some parts where old collapses had left rock piles, leaving us in only 5m of water.
Steffi carefully installed her experiment, tying it off in the roof of the cave.
Tree roots hung down around us and in one corner we could see the light streaming in through another entrance, silhouetting more tree roots. This was made even more dramatic by a tropical storm which had broken since we left the fresh air above, creating random blue shafts of light which flashed with the lightning. Hammer House of Horror meets Jean-Michel Jarre!
This area is called the Skylight Room. Some say it is possible to snorkel the 100m from our entrance to this hole where water meets air, but I think it would be unwise to try! This is real cave diving, to be given the respect it demands.
In one corner, at least 50m from the nearest entrance, lies an old black rubber fin. Steffi later told me that it had been there since before the cave was first officially dived. I could imagine the panic of some itinerant snorkeller lost in that dark place, and losing a fin in the mad scramble to find the way out.
Naturally we had the benefit of permanently laid guide lines, but in such a vast space it was easy to lose sight of the thin white cord if one ventured far from it without clipping on your own line first.
At one point it becomes impossible to see because of a halocline caused by the intermingling of fresh and salt water.
Leaving the first chamber, we set off downwards through the strong halocline. The original guide line had become broken at this point so Steffi went on ahead to replace it.
Once she had moved more than a few metres from me I could still see her lights but it was impossible to focus my eyes on her.
With the line safely tied off, she came back and escorted me onwards. As she led the way, I noticed how her fin tips were making the water go wibbly-wobbly.
This soon increased to the point where our vision was so disturbed that our masks became redundant. It was at this point that I realised I could not see the guide line even in the beam of a powerful light.
At about 23m, the freshwater element of the mix was left behind and we regained perfect vision. Steffi searched for a previously laid experiment among the colourful mung on the cave floor. "Mung" is a word used to describe the bacterial detritus that lies 28m down on the cave floor, and you need to watch out how you use your fins when it is around. Stir up the mung and you'll soon be feeling your way back!
Next we ascended into the Wedding Hall Room. This is a chamber full of stalagmites and 'ctites and it provided the best photo opportunities. Here Steffi checked another of her experiments while I used up the film in both my cameras.
Earlier I had asked her about the purpose of these experiments, which were connected with work for her Phd.
"I'll keep it simple," she had told me. "We need a better understanding of the underground ecology. The caves are windows into the underground world that allow us to observe first-hand what the water and the biological processes are doing in their natural surroundings.
"The knowledge we obtain allows us the possibility of solving pollution problems elsewhere in the world where access isn't possible."
There seemed no point in continuing the dive, as my films were used. I wanted to go back for a reload and signalled to Steffi.
I started to swim off in totally the wrong direction before coming to the next direction arrow attached to the guide line. It pointed the other way and I learned a swift lesson in how easily one can get disorientated in these conditions.
Most accidents in cave diving have been associated with the loss or absence of a properly laid guide line, and in this case the attached direction arrows proved just how essential they were. I estimated that at this point we were a couple of hundred metres from the entrance.
We carefully made our way back, with Steffi pausing to check a third experiment involving specimens of bacteriological material. We moved up through the halocline and back into fresh water, past the eerie shafts of daylight with the tree roots, and finally back to the entrance.
It was a great feeling to have done a saltwater dive and yet rinsed all our kit in freshwater before we regained the surface. These freshwater "lenses" are an important source of drinking water for the Bahamas.
Steffi helped me carry my gear back to the car. She has learnt that to survive in what has traditionally been the man's world of cave diving, you have to be tough. But the toughness she shows on a dive belies a surprisingly gentle interior.
"The purpose of the Rob Palmer Blue Holes Foundation is not merely to explore and investigate these caves," she says. "We want to share the wonderful experience of diving in them with a wider public.
"We run several Blue Hole expeditions every year. And it's a good idea for every diver to do a cavern-diving course. Even though you may never cave or cavern dive, the skills you learn stand you in good stead in all aspects of open water diving.
Steffi's story
THE Rob Palmer Blue Holes Foundation is alive and well," says Steffi Schwabe. Widow of the late Rob Palmer, Steffi was the academic while her husband was the front man for the now re-christened foundation.
Geologist, soft rock sedimentary petrologist, geomicrobiologist - Steffi Schwabe is something of a boffin if 'ologies count!
Born in northern Germany in 1957, Steffi moved at the age of seven to Charleston, South Carolina, USA, with her parents. She comes from an academic family; her father is a biochemist and her mother a research assistant.
In her youth she was a competitive free-style swimmer and springboard diver at inter-collegiate level. She was also into wood-working, oil painting and sculpting with clay. She won trophies in sailboat and cycle racing, she was a competitive rollerskater, and on ice she was into figure-skating, free-style and dance.
In 1978 she started studying medicine but abandoned it after seven years to do a BA in geology, followed by an MSc in petrology and the Phd she is currently working on, which involves the biochemical investigation of caves within carbonate platforms.
Steffi is no shy retiring academic. She was the boss of the lifeguards at Charleston for three years - don't confuse that with the girls of Baywatch! She learned to scuba-dive at the age of 20, and within a year she graduated to cave diving in the Florida spring systems.
She met her future husband, Rob Palmer, in the Bahamas and they were married at Oban in Scotland. Together they started what was originally called the Bahamas Blue Holes Foundation, recently renamed in honour of her husband, who was tragically lost during a leisure dive on a coral reef in the Red Sea.
Appeared in DIVER - November 1997
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