Q: What's the difference between the Phoenix, the bird of ancient Arabian legend, and Mark Ellyat, the holder of the world's deepest solo dive? A:The Phoenix rose from the ashes of seeming defeat to soar high in victory; Mark recently sank from the heights of seeming defeat to victory.

Phuket based diver Mark Ellyat recently broke the world record, at 313 metres, for the deepest solo dive. The 34-year-old Londoner first started diving 14 years ago. Since, he has done a 10-year teaching stint that has taken him from the Channel Islands to the Bahamas to Australia and eventually, four years ago, to Phuket. Nowadays, Mark teaches at Scuba Cat Diving, in Patong. After suffering a major setback last February, when his test dive ascent went decidedly awry, he fought his way back to fitness, breaking the world's solo diving record in December 2003.

Most people's idea of a world-record breaking attempt doesn't include des-cending to over 300 metres underwater in pitch black darkness and a water temperature of 4 degrees centigrade. But not everyone shares the same passion for deep-water diving. Deep diving and shallow diving may be cousins, but, on closer inspection, they more resemble distant family relations. To appreciate the Briton's achievement in perspective, consider the following: most divers descend to a comfortable 15 metres, maybe 30 at a push. The surface water temperature surrounding Phuket hovers within a couple of degrees of 28 degrees centigrade. Most shallow divers, further-more, have no need to urinate constantly or to drink three to four litres of water an hour to compensate for the immersion diuresis that occurs at extreme depths.

Last year, Mark felt as though he'd dived for the last time. In the first major negative incident in a career that has spanned more than 3,000 dives, and in preparation for his record-breaking dive, he descended to the depth of 260 metres. He used commercially available diving software that had never before been tried and proven. He says, in retrospect: "It had no place suggesting it could provide an ascent solution from a depth well within its stated specifications." As a result, Mark's inner ear was damaged. His equilibrium was affected so badly he couldn't walk for two months and, even after he regained his feet and went out, he was often mistaken for a legless inebriate.

He'd stumble into a Patong bar at six o'clock in the evening only to be politely but firmly escorted out by staff members. "I went to McDonald's early one morning, and they refused to serve me, thinking I was hopelessly drunk — and they'd serve anyone there!" Thankfully, the condition improved, with Mark making "a miraculous recovery". Even so, his doctors advised him to never dive again. But it's hard to drop a 14-year long career and an ardent love of a sport.

How does Mark feel about the sport? "Successful extreme deep diving is a complex business. It's not really a competitive sport. In fact, you're competing only with yourself and, if you lose, you lose the farm." So who typically goes in for deep diving? "It attracts a lot of oddballs," he says. "Ex-military types and ex-bouncers, for example. People who like it hard."

Mark's main motivation for the dive was to promote tried and proven safety standards. "My purpose in attempting this deep dive was to find some answers and to prove some theories. I wanted to add a bit of credibility to the [safety standard] process. As a result, people like the special operations branch of the US Navy have contacted me; they're not willing to risk their own divers in these kinds of tests. If things go wrong, it's not a case of 'give them a pill and they'll get better'. The rest of your life can be affected. They want my findings."

And the $64,000 question: What's it like down there? "Lonely; like a trip to the moon."

But why Phuket? Well, at 200 metres below sea level, two world-wide constants apply. Firstly, surface light dies, with total darkness ensuing from 180 metres. Secondly, the water temperature drops to 4 degrees centigrade. So the chosen location for the dive, 60 kilometres off the west coast of Phuket, was equal to any. Considering relative surface visibility and decompression chamber availability, furthermore, it had distinct advantages. "Phuket treats its divers seriously, and you never need be more than an hour from a recompression chamber. And our rescue boat had a 900-horsepower petrol motor bolted to the back."

Surprisingly enough, Mark's descent took just 12 minutes. "A dive deeper than 300 metres needs a rapid descent." He checked the depth on the taped measurements on his plunge line with head-mounted lights. Although his dry suit kept the warmth in, he started to shake. He couldn't decide whether this was from the cold or from helium gas-induced tremors. (A note for divers who are loath to go through the correct safety procedures: "At 280 metres down, I didn't seem overly concerned. And this concerned me!")

At 313 metres his self-planned dive schedule was running one minute over, and his constant mental safety checks seemed to be getting more and more complacent. At this point he looked down and saw the ghostly image of some kind of large hydroid. "I scanned left to right to check for any visual abnormalities and to check the distance more exactly of my jelly-like visitor," he says. "The little checks I did told me that my concentration was sometimes stalling into a complacent mind-lock, and this set the narcosis alarm bells ringing."

This two-metre hydroid looked on course to hit his descent line. "I checked the depth on the line," he says. "It was deep enough for that day. I grabbed the line marker at 313 metres and headed for 249 metres, the first deeper stop. Mark shut his eyes and ascended hand over hand. "The time spent at lower depths is crucial to the survival of a diver. The longer you stay, the more risk you run." But, if a repeat of last February's misfortune was to be avoided, it was vital to stick to plan during the painfully slow ascent of over six hours.

Then began the long wait while Mark's body accustomed itself to just-below-surface levels, all the while obtaining necessary oxygen through long regulator hoses from the mother boat above. At this point, an accident that would have been comic in other circumstances occurred. His tongue almost got sucked through the regulator, causing the hose to collapse briefly. "This was very unpleasant, but could have been much worse." Mark laughs. "A small communication problem, I think."

During the stops, he ate fun-size Mars Bars and banana pieces while the support divers were having their lunch. "I knew this was the case because of the chicken bones that were raining down around me. Small fish started closing in, pecking at all the goodies. I hoped a toilet flush wasn't coming next."

At last, after 6 hours and 36 minutes under the Andaman Sea, it was time to surface. "I had got down deeper than any solo diver before me," he says. "I had surfaced under my own strength and, more importantly, without decompression illness. Although I was exhausted, I was very happy." He was soon being féted by reporters from local and national press, including the inter-national dive magazines.

Does a long, fulfilling career in diving beckon? "No!" he says. "The best time to get out is now. I'm not going to make my fortune out of diving. Plus, the number of people coming to me for deep-water training just exposes me to more risk. And, as long as you're in the dive industry, the Ferrari and the luxury yacht will have to wait."

But if you're as daring and as visionary as Mark Ellyat, glory and world-wide acclaim could well come your way. And that's not a bad trade-off.

Marc Morin is a saturation diver. When he's at work, he lives in a diving bell, spending 8 hours a day about 75m beneath the sea. He and his colleagues are pressurized to the equivalent of a depth of 80m with a mix of helium and oxygen, and stay in that state till they're decompressed at the end of their assignment. Basically, he and a team of six other divers, three teams of two, get down to the nuts and bolts of oil rigs and ensure all is well in the depths. It's an essential job, and a job that must be performed by humans. Someone's got to do it, as they say.

I went to meet Marc, a quiet, gentle man, at his home in Chalong Bay. He lives here in Thailand with his Canadian girlfriend Simone and, when he's not out at sea working at the base of oil rigs, he's either at the gym or out diving off the coast of Phuket. Yes, diving again. You would think that he'd want a break, after all that time underwater, but he loves the sea. He says he prefers being outdoors, and has avoided working in buildings wherever possible. The weird thing is, he actually feels like he's working in an office with this job, since he's in the "box" for so long. "The only freedom," he says, "is when we get out of the bell to work."

Marc was born in Quebec 30 years ago, and started taking scuba-diving courses around the age of 17 in freezing Canadian waters. He earned a BSc in ecology and biology before setting out to find suitable work. First, he took a more serious diving course. After qualifying as a commercial diver, he worked on bridges and dams with hydro-electric companies in Ontario and Quebec. He then moved out to Asia, got his Saturation ticket and has been living here for four years.

He stays at home in Chalong until the phones rings. The call might come from any one of a number of diving companies hired by construction outfits who build oil rigs. Following a short discussion, a contract is agreed upon and Marc sets off for the rig. These contracts can take him anywhere there is oil, but recently he's been working off Thailand's Eastern Seaboard. Once on the rig, Marc and a few fellow divers collect their gear together — little more than diving gear, a cell phone, a personal stereo and maybe a book or two — and say goodbye to the rest of the world before entering the "box" — a chamber with just enough room for bunk beds and a toilet.

Once inside, the guys settle down in their bunks and the cylindrical hatch is sealed. Then, from a huge control room that will be the life support machine for the duration of the job, helium gas mixed with oxygen is pumped into the chamber and the men are pressurized until they are at the same pressure as their working environment — typically between 7.5 to 14 atmospheres. From the same control room, the divers will remain under constant surveillance while in the chamber — everything they do and say can be heard and seen and any problems monitored.

"You don't feel strange while being pressurized," Marc says. "In the past, they used to use a nitrogen mix that had a hallucinogenic effect, so we all got a bit weird, but these days its helium and oxygen and the process only takes an hour. We get pains in our joints a lot but otherwise not many problems." As he described a typical day, pictures of astronauts and the moon came to mind — total opposites, in terms of their situations relative to the rest of us, but very similar for all of that.

By 6pm, the divers get hungry. Dinner is passed into the chamber through a special hatch and pressurized to the same level before it can enter. If it weren't, it could explode. Dinner over, it's a phone call to girlfriends and family, a little reading and off to bed. The guys work around the clock in eight-hour shifts, so there's always someone in the sea and someone in the chamber.

"When it's your turn to go under," says Marc, "you take only a diving suit with you and crawl through a hatch into a bell which has been locked on to the chamber from the outside. There is very little space in the bell — enough for two divers and a tiny area for changing into our suits, but no room to stand up. The bell has weights attached to the bottom, and we are lowered by an A-frame into the sea, down to about 10m off the seabed. It takes about 30 minutes to get there.

"We change into our suits and attach ourselves to 50m of "umbilical cord", and then leave the bell. Work starts immediately. We are jacks of all trades." Marc laughs. "In this line of work, you have to be able to problem-solve and use your initiative. A good diver can fix anything down here. We attach pipes, scrape marine growth off equipment, hook pipelines up between platforms, cut steel — all sorts of jobs." He was so enthusiastic while telling me all this that I could tell he was a man who took his work seriously.

But it's not all work. "Some of the platforms — the base of the oil rigs — have been down there 10 years or more," says Marc. "When they're that old, they're like giant reefs, teeming with marine life. It's fascinating to see the thousands of colours and all the different shapes and forms of creatures living on the legs of the rig. You have to be careful where and what you touch, as some of these things are dangerous. Some of them we just don't know, because we've never seen them before. We also see giant barracudas and whale sharks and many species of fish that, as yet, have no names."

So what's the toughest part of saturation diving? "The hardest thing for me was getting used to becoming fast and efficient at work under pressure at such a level and for so many hours," Marc says. "I'm a perfectionist, and I like to challenge myself to do the best I possibly can in my work. I admire professionalism.

"It's also a bit difficult with personality clashes sometimes. We don't always know each other before we're together, in this job, and occasionally there are differences of opinion. I also miss my girlfriend, obviously, but we have a great relationship and she is very understanding and accepting of the situation. You get into a sort of routine and then, when you're back on shore, you have more quality time."

Just then, our conversation was interrupted by the telephone. It was the call. Time to go, for Marc. As I sauntered out into the Chalong sunshine I looked out to sea and felt quite contented to be on dry land.