Colleagues affectionately call Dr Sylvia Alice Earle "Her Deepness". And American publications have dubbed her "Queen of the Deep", among other highly complimentary titles.
Sylvia Earle makes light of them all, but there is absolutely no doubt that she deserves them. For this diminutive, attractive, highly articulate and passionately committed lady from New Jersey, USA is, among her other remarkable underwater accomplishments, the world's deepest woman diver. In 1979, for instance, she made the world's deepest solo dive, a record of its kind that still stands. Contained in the one-atmosphere armoured diving suit JIM, she was strapped to the front of a small research submersible and taken 385 metres down off Hawaii. Untethered, she then walked the seabed for 21/2 hours.
At that time, only submarines had reached that depth, and she was later to say that what she saw amazed her - including coral that pulsed with blue light, sharks 18 inches long, and fish with little lights "that cruised by like miniature ocean liners".
But Sylvia's love affair with the underwater world began much earlier than that, as did the amazing record of her achievements. At the age of 16, when her family moved to the west coast of Florida, she had the Gulf of Mexico on her doorstep, and spent much of her time cataloging the plants and animals in the water.
Aiming for a degree in botany, she wrote a thesis on the algae of the Gulf, started a collection of marine life samples, and now has 20,000 of these. Using early examples, she is now able to identify changes in the marine habitats of the Gulf, which today adds to her worries about the future of life in the sea.
Her teenage studies were quickly to earn her a Bachelor's degree from Florida State University, then a Master's degree from Duke University.
She was 17 when she persuaded the owner of hardhat diving gear to let her try a helmet dive in Florida's Weekiwatchee River. What she saw fascinated her. And when the sale of scuba diving equipment began in the States in the early 50s, it seemed only natural for a girl who had studied seaweeds and dived in a hardhat to become one of the first women to use the aqualung for marine biological research.
Soon Sylvia Earle was identifying previously unrecorded undersea growths and creatures, and her reports about sand dunes on the seabed off the Bahamas caused an upset in the world of oceanography.
Her achievements in the following years read like a diver's dream. She quickly became one of the leading experts on marine ecosystems and plants, and she is now one of the few women oceanographers of note.
Honorary doctorates and awards have descended upon her like confetti. She holds the Prince of the Netherlands Order of the Golden Ark; the Department of the Interior's Conservation Award; the Geograph-ers' Gold Medal Award, the American Academy's Golden Plate Award, and others far too numerous to mention. Along the way she had a sea urchin (Diadema sylvie) and a marine plant (Pilina earli) named after her.
But it is her underwater exploits that really grab the attention of the majority in the diving world. In 1964, she was in the Indian Ocean aboard a National Science Foundation research vessel for six weeks. Then there were underwater expeditions to the Galapagos Islands, the Juan Fernandez Islands and the Panama Canal area.
But her really extraordinary diving experiences began in 1968 when she and several other scientists went down to more than 30m in the first modern submersible with a lockout chamber.
This allowed divers to swim out of and return to the submersible, and Sylvia was four months pregnant when she became the first woman scientist to lock out of an underwater vehicle.
Then came the Tektite Project in 1970, sponsored by the US Navy, the Department of the Interior and NASA. This involved several teams of scientists living for extended periods of time in underwater habitats on a Virgin Island coral reef.
Sylvia led the first team of five women aquanauts to undergo this experience, staying for two weeks beneath the surface, performing marine research outside the habitat, and, among other things, surviving an underwater earthquake.
The media called the team "aquababes" and Dr Earle became a national heroine, receiving a ticker tape parade in Chicago and an invitation to visit the White House.
Tektite, however, changed her view of the underwater world, giving her an insight that she had never known before. It was to lead to her conviction that the sea is vital to the survival of the world as we know it, and to her passion for its conservation.
Immediately, however, it led to further deep-sea exploration, beginning with that record dive in the JIM suit in 1979.
It was then that she met and married Graham Hawkes, a brilliant US-based British engineer who had improved and modernised the original JIM suit that had been developed by another Brit in England, Mike Borrow.
In 1981 Sylvia Earle and Graham Hawkes started their own company, Deep Ocean Engineering Inc, to design, build and sell underwater robots and submersibles.
Their own personal ambition, however, was to develop the means to descend to and explore the greatest known depth in the ocean, the 10,915m Challenger Deep in the Pacific's Marianas Trench. This has been reached only once before - in the bathyscaphe Trieste, piloted by Swiss scientist Jacques Piccard and US Navy Lt Don Walsh in 1960.
They describe their project to explore these huge depths as "the Ocean Everest Expedition", though the 11km-deep trench is 1800m deeper than Everest is high.
By 1984, the new company had produced a one-man submersible, Deep Rover, designed for inspecting oil rigs. It was in this that Sylvia went down alone to some 1000m.
The million-dollar company went on to build not only deep-sea manned submersibles, but also remotely-controlled robots for the offshore oil industry. To diversify, Sylvia became the founder-chairman of another company, Deep Ocean Exploration and Research Inc.
In 1990 she was the first woman to be appointed Chief Scientist of America's National Oceanic and Atmospheric Administration (NOAA), a Presidential appointment confirmed by the US Senate. And as such she was the first marine scientist to be flown to Kuwait to monitor the effects of the deliberate dumping by Iraq of six million barrels of oil into the Arabian Gulf, the worst pollution by oil in history. She had also served as an adviser in the aftermath of the Exxon Valdez spill in Alaska. She resigned her post in 1992 after only 18 months because she had a deep conviction that people need to be better informed about the growing threats to the oceans of the world, and wanted the freedom to do this. At the time she said: "I am suffering from dry rot; I want to spend more time underwater".
And so she did, plunging back into her lifetime mission of cataloging all the plant life in the Gulf of Mexico, expanding her observations of the behaviour of humpback whales, pushing the cause of marine sanctuaries, and, most of all, planning and preparing for her ultimate underwater adventure in the Challenger Deep.
Sylvia has spent more than 6000 hours underwater, including some 1000 hours in saturation, and has led over 50 expeditions.
Such an extensive underwater career has been relatively incident- free. She has never had the bends, but once when studying marine growth on Japanese wrecks in Truk Lagoon she was badly stung by a lionfish. In intense pain and close to death, she was helped by underwater photographer Al Giddings to a decompression stop, where she hung in great distress for nearly an hour. Having devoted her life to exploring the sea, Sylvia is now bent on trying to save it.
She describes the ocean as a balance sheet increasingly out of balance. "I'm not a doom and gloomer but I feel a sense of urgency about the extent of our ignorance," she tells Diver. "But we have the ability to turn things round. If we had kept to the policies of 50 years ago we would have been the last to see the great whale species.
"If we know better, our commonsense and self-interest will cause us to do better. Divers are the best-placed people in the world to understand the importance of this, and should realise what a special window we have on the sea.
"People without masks or flippers simply don't appreciate that every spoonful of ocean is filled with life. It's a matter of what those of us who have that special window can do. We are ambassadors for the fish and all those other creatures out there. I hope that we can all accept the responsibility for making things better in the oceans.
"The trouble is, there aren't that many divers on the streets. I was recently with a group of students in Texas. It turned out that less than half of them had seen the ocean. There was less than a scattering of hands when I asked how many had actually put their big toes in the water. And only three of the 200 students had been underwater.
"But head up and shoulders back, it's easy to look at the flipside and think: what an opportunity!" She is at this time on the boards of the World Resources Institute, the Centre for Marine Conservation, the Natural Resources Defence Council, and the Lindbergh Foundation. She is also on the Advisory Council of the World Wide Fund for Nature, President of Deep Ocean Exploration and Chairman of the Caribbean Marine Research Centre.
It would be difficult to find a better person to deliver the Oscar Gugen Memorial Lecture at this year's Diving Officer's Conference (November 30/December 1).
Always a great supporter of British diving, she has been a guest presenter at three of the renowned Brighton Conferences organised and presented by Diver Magazine.
Though now divorced from Graham Hawkes, the two are still closely associated and intent on achieving their ambition to explore the ocean's greatest depth.
Their plan is first to send down an unmanned submersible to transmit pictures from the Marianas Trench. Deep Flight II will follow. This 6m-long submersible, looking something like an aeroplane with stubby wings, is set to 'fly' over the seabed 11km down at speeds of up to 15 knots.
Graham Hawkes will be at the controls - but Her Royal Deepness will be down there with him.

In these brief words, in the first chapter, marine scientist Sylvia Earle sets the scene for her latest book, Sea Change: A Message of the Oceans. (Constable; 18.95). However, the book is more than the story of the watr-logged life of one of the most amazing women of our time. Sylvia Earle has spent more time underwater than any diver in Britain today - or America come to that. Perhaps only Cousteau has seen more of life underwater than she has. And, like him, in recent years she has not liked what she has seen down there.
Her problem is how to alert the decision-makers to what is happening under the surface of the Earth's seas. She writes: "I came into contact with a startling number of bright and influential people who seemed not to know or care that the sea is changing, and that the fundamental underpinning of all that we hold dear as humans is jeopardized by such ignorance and indifference.
"I wondered what could jolt people from their complacency, could make them notice the dangers of overfishing, of poisoning the sea with toxic chemicals that return to us in intricate but inevitable pathways, and of blindly tinkering with Earth's life-support mechanisms."
The book is part of her attempts to wake us all up. She escorts us in the pages of her book through her diving life, and a good diving read it is, yet in most of her stories she is able to point out the evil way we are treating the sea and the creatures in it. Don't fear that the book is a do-gooder's bible - all ordinary divers will recognise seabeds they know and creatures they have seen and will understand what Sylvia Earle is saying.
She is warning the world's decision-makers that as far as the oceans are concerned, unless we all do something and do it soon, the sea will reach "the point of no return" and then quite simply the Earth and all that lives on it will die.

Kendall McDonald