Horizontal in the water, making a star shape with our arms and legs, fingers and thumbs wrapped loosely around the metal cable shotline, we descended. The white top of the diving bell, 30m below, loomed through the green water. The Underwater Centre, 01397 703786, www.theunderwatercentre.co.uk
"Diver One, surface," crackled a voice in my full-face mask "Have you reached the bell yet?"
"Diver One, reached bell," I replied, climbing down the side of it.
Inside were a set of pipes and quarter-turn valves, and the top third contained air supplied from the surface. Almost weightless, but not quite, I bounced around outside the bell on a lifeline.
It felt as close to being on the Moon as I could get while still on Earth.
I was on the HSE Scuba (Part 4) commercial air diving course in Fort William, Scotland. For photographers planning to work under water, holding this certificate is a legal requirement. Many potential clients won't commission you without it.
The first six days of the four-week course had been spent in a classroom studying theory - first aid, oxygen administration, use of US Navy decompression tables and diving physics. It was fairly intensive, with homework most evenings.
Then we began diving. Starting each day at 8.30, we took turns to dive, refill cylinders, tender, record details of the dive and handle the radio.
This is a very different way of diving. Each diver wears a harness and lifeline and works with a "tender" on the surface. Our initial dives were carried out using normal scuba-diving masks, known as half-masks, and demand valves. Many were done without the use of fins or a BC, and we communicated with the tender using lifeline signals consisting of "pulls" and "bells". Pulls are slow yanks on the lifeline; bells are short, sharp jerks, made in pairs.
We quickly moved on to the Exo 26 full-face mask with hard-wired voice communications. It was comfortable enough to wear, and being able to breathe through my nose and speak under water seemed a real novelty.
My breathing sounded as if Darth Vader was wrapped around my head. I had to hold my breath when being spoken to, or the loudness of my breathing would smother the other voice.
"Diver One, are you well?" crackled a quiet voice.
"Diver One is well."
"Find a pieckck, crackckle, hisss, crakckcle and tie crkackcle, crahckl."
"Say again," I replied, quickly snatching a breath to hold.
"Crackckle, a piece of scrap metal and ckrackel crak hiss tie on to the rope's end with a bowline."
"OK surface, understood," I said, hoping that I had.
Bouncing along the bottom, I tried not to step too heavily on the muscular orange starfish that carpeted the seabed.
I found a small piece of rusty metal; it looked insignificant compared to the big chunks I had seen the boys before me send to the surface. But finding nothing bigger, I made my way to where a rope and shackle were dangling, secured my find with a bowline and gave a lifeline signal to the tender above, telling him to pull the line to the surface.
Rescue practice is an important part of the course. We practised both in-water and surface standby rescues, for which two divers are sent to the bottom in different directions.
The standby diver stays on the surface, kitted up ready to dive, and one of the in-water divers is told to act unconscious. The standby diver leaps in to the rescue, following the unconscious diver's lifeline.
Rescues using the full-face masks and comms require a running commentary of exactly what is happening during the rescue:
"Diver Two left surface, following Diver One's umbilical. Umbilical is clear of snags. I can see bubbles. I can see Diver One.
Diver One is breathing but appears unconscious. I am looking to see if it is safe to approach Diver One.
"Area is safe to approach. Flushing Diver One's mask [with air]. Checking
bail-out. Main cylinder one two zero bar.
I am securely holding onto Diver One. Bring both divers to surface..."
The casualty's tender pulls hard on the lifeline while the rescuing diver lifts the casualty to the surface using his suit inflation or BC if worn.
The divers reach the surface close to the exit point, and the tenders pull the casualty out of the water.
We also did visual inspection reports and grid searches, including one in zero visibility. We set up a jackstay search and we each had to do a seabed search, blindfolded, hunting for a shackle.
My turn came, and I was called up the steps to have Gaffa tape stuck all over the front of my mask. Diver Michael Moore came back up the steps from the seabead to lead me back down to the jackstay.
This was great fun. I went charging up and down the jackstay, holding it loosely with one hand while making big sweeps with my other arm. I was sure I would find the shackle, but apparently went over it twice and missed it. Mike did better, and found it when it was his turn.
There were two night dives, one beginning at 3am, using half-masks and DVs, lifeline signals and surface marker buoys consisting of a buoy and a length of coiled rope - very different to the small inflatable SMBs with a tiny reel of line used in sport diving.
Holding a coiled SMB rope too fat to fit comfortably in one hand, along with a lifeline and torch, and to play out the floaty SMB line while descending the hill, proved challenging. Near-zero visibility didn't help.
Nitrogen narcosis can affect any diver breathing air at depth, and a chamber dive demonstrated this. Fellow-student John Williamson and I were given sheets of paper covered in lines of continuous, random letters. We had a minute to circle as many letter Cs as we could find. Then we were given identical sheets to take with us into the chamber, which was quickly blown down to 45m and became really hot.
John's voice became squeaky and high-pitched. I got very giggly, feeling as if I was fairly drunk and light- headed. John started acting drunk, too.
Alf, our tutor, was operating the chamber. He asked us to look for the letter E this time. I was surprised at how easy it was to stop giggling and concentrate on the task.
I felt OK while doing the exercise, but I had scored 23 Cs before entering the chamber, and only 18 Es inside.
Alf started to bring the chamber back to the first safety stop. It got really cold and filled with mist. On our second safety stop we breathed oxygen from a mask for several minutes.
At the end of the course, we sat written exams on diving at work (mostly legislation), scuba diving and US Navy tables. There was also a practical first-aid test.
The scuba course finished a couple of days early, but some of the divers had catch-up dives to do from a surface-supplied diving course they had done earlier. I took part too, wearing a harness with a bail-out cylinder and a Kirby Morgan 17 helmet. This seemed to weigh a tonne on land, but once in the water felt really comfortable. Breathing air was supplied through an umbilical.
I climbed down the steps to the seabed and walked with student diver Conrad Wesley to the welding station.
Using ultra-thermic cutting equipment, Conrad cut a slice from a chunk of metal in a shower of bright sparks. The cutting tool is fed with pure oxygen and burns at 10,000°F.
I took photographs, and found the surface-supplied KM17 much easier and more comfortable to work with than scuba equipment. It has a far wider angle of vision than half-masks or the Exo 26.
Breathing seemed as normal as if I was on the surface and the helmet was very quiet - without the Darth Vader effect, the voice communications were very clear and easy to understand.
Conrad completed his task and offered me the cutting tool. I struck the metal with it as if it were a giant match, trying to generate sparks to ignite the oxygen, but the tool kept sticking to the metal.
I finally got the hang of it, and watched fascinated as the glowing oxygen turned the solid metal into a molten liquid that fell away in globules as I drove the tool downwards.
The following day Punkaj Singh, also a student from my scuba course, needed to do a surface-supplied rescue assessment catch-up dive from the diving bell. I was invited to dive with him.
The bell was on a barge and would be lowered via a winch through a square hole in the barge known as a moon pool.
We entered the bell wearing hotwater suits, in which a continuous supply of heated water is pumped around the diver. We used Kirby Morgan 28 full-face masks, with air again supplied from the surface through an umbilical.
Kneeling in the bell, we were lowered to within 1.5m of the seabed. It was very dark beneath the barge.
I climbed onto the side of the bell, unwound my umbilical and left it, walking down the hill as far as the umbilical would allow. I then pretended to be unconscious. Punkaj was told that
I was in trouble. He left the bell and followed my umbilical, flushed my mask with fresh air and checked my bail-out.
I was dragged back to the bell and my head secured above water, inside the bell's air space. The rescue completed, we were able to leave the bell again and wander around the bottom.
There were lots of hermit crabs and silt and we were as toasty-warm as if in a hot bath. I wanted to stay and do the surface-supplied course too!
I had felt a bit out of place on arriving at the Underwater Centre, being the only female there, but my fellow-students had been very sociable and I had soon felt at home. There were eight students on the scuba course, and others training as surface-supplied and saturation divers.
At weekends we walked up the spectacular mountains and swam in the rivers around Fort William. Friday and Saturday nights we headed into town and had fun in the local bars and clubs.
Four HSE certificates cover different types of commercial diving. The Part 4 course I did covers those working in media, scientific and archaeological, recreational and inshore diving using scuba gear. Parts 1 and 3 cover surface-supplied and Part 2 closed-bell diving.
These courses are for divers working in a range of construction environments, from inspecting bridges to spending a month at depth working on oil pipelines.
There are also courses for using tools, non-destructive testing and operating remote operated vehicles (ROVs).
I was already an experienced freelance photographer working in the marine environment and a recreational diver, so taking my camera under water was a natural progression. And I was lucky - my course, plus tuition from leading underwater photographers Linda Pitkin and Martin Edge, was funded by the Queen Elizabeth Scholarship Trust, which helps craftspeople to develop their skills and careers (www.qest.org.uk).
Michael Moore, in the full-face mask, grasps one of the bell's cables, being used as a shotline
John Williamson on a 3min simulated deco stop - the shackle is the "lazy shot"
marking 6m below the surface; an ultra-thermic cutting tool in use
the Red Baron diving barge on Loch Linnhe, Fort William
Conrad Wesley cuts through metal using an ultrathermic tool
The Red Baron diving barge, moon pool and bell.