Oceanographer Dr Sylvia Earle is arguably the ocean's biggest champion, with six decades of first-hand experience in the world's big blue backyard.

It was a rogue wave on a New Jersey beach that first sparked the then 3-year-old Sylvia Earle's interest in the sea.

Now in her 70s, Dr Earle has a job title that would send thrills through the imaginations of most children: "Explorer".

The oceanographer has more than 6000 hours of deep sea diving behind her, and holds the women's record for walking untethered at the lowest depth. Her life of deep sea diving has earned her the nickname "Her Deepness" in America.


Earle said it started on that New Jersey beach when a wave knocked her over. After the initial panic came exhilaration.

"All children are like that, all explorers. Every child has that nature of wanting to know what is under the next rock or around the next corner. Scientists never lose that childlike curiosity, that sense of wonder."

She is one of 12 of National Geographic's explorers-in-residence, entitling her to research and expedition support and office space.

Not that she sees much of it - "Explorer in residence" is a slightly oxymoronic title and Earle chooses to emphasise the "explorer" portion.

Compared to other explorers, Earle explores in relief. While most see the world as land interrupted by sea, Earle sees the world the other way round - as ocean occasionally interrupted by land.

The Cook Islands and other Pacific Islands only have small land areas "but they have very large blue backyards". And there is far more untouched territory in her world.

"Only about 5 per cent of the world's oceans have ever been seen by anybody, so there's plenty to do forever to keep people occupied, including myself."

She says the fascination for her is the amount of life in the ocean - from the big to the small. "Every drop of water has life in it. The ocean is like a big minestrone. It's the soup of life."

One of her concerns is that humans seem hell-bent on scooping all the chunky bits out of that minestrone. So when she is not underwater, she is working for conservation groups, bending the ears of politicians.

Sometimes there is good news. She has lent her voice to several conservation groups - and it was her link with Conservation International that took her to Rarotonga in the lead-up to the Pacific Islands Forum a fortnight ago.

She was there to cheer on the Cook Islands as it launched its million square kilometre marine park with carefully chosen allocated areas for conservation, recreational and commercial fishing.

She found a kindred spirit in former league player Kevin Iro, who is now raising his six children in the Cook Islands and was one of those who pushed for the marine park.

He had told her that he wanted his six children to know the same ocean he had known as a child, but he had already found it much altered. Happily, Prime Minister Henry Puna agreed.

And sometimes there is the bad news, as there was this week when the United States' efforts to broker a joint proposal for a marine reserve with New Zealand failed - despite public backing from influential Secretary of State Hillary Clinton.

The US had wanted a larger reserve with greater protection against fishing, but New Zealand - one of the countries that fishes toothfish in the Ross Sea, refused. Earle is one of the "big names" alongside Richard Branson and actor Edward Norton who are on a consortium of environmental groups pushing for a large marine reserve - and a ban on fishing of toothfish - in the Ross Sea.

Branson and Norton bring the famous faces and the money to the Antarctic Ocean Alliance, but Earle is arguably a more potent weapon. She is harder to argue with for a start - she comes armed with credibility, science and six decades of first-hand experience of the bottom of the ocean.

She says the nations of the world agreed to protect the land of Antarctica from commercial development decades ago - but have ignored that blue backyard.

She is a champion of one of the smallest ocean-dwellers - the krill that feed the medium fish that feed the big fish. To the peril of the ocean, the people eat them all. Earle calls krill the "anchor" of the Antarctic - feeding birds, squid, whales, seals and other fish, and eating the phytoplankton. She wonders why people are now intent on mincing it into fishmeal to feed to cattle and pigs instead.

Earle is also a champion for the other end of the food chain and is one of the few people who goes into the water actually hoping to see sharks. Lots of sharks.

The scarcity of sharks was one of the things she noticed about diving in Aitutaki this time round, compared to her first visit to the Cook Islands more than 20 years ago. She saw only one during several days of diving, compared to dozens on that first trip.

She estimates that 90 per cent of many of the "big fish" have now gone, a victim to the dinner plate.

Hence she is as evangelical about fish as a vegetarian is about beef.

She can't stop people eating fish, but she does wish they would ask a few questions before they did - such as what kind of fish they were eating, how it was caught and how old it was.

"It doesn't make sense to eat fish that are older than you, or even your grandparents are. Like orange roughy, they can be 100 years old or more. They appear on your plate and they're gone in 20 minutes."

Though it's easy to make a case for "cute" animals like dolphins, pandas, penguins, it's harder to get the public to think fondly of a fish.

"We look at snow leopards and we say 'ooh beautiful, we must protect snow leopards'. We look at tuna and we say 'mmm, delicious'. You might want to continue eating fish, but let's not eat all of them."

She did eat fish once - "more than my fair share" - but no longer does.

"I choose not to because I value them more alive than dead."

She points to the Ocean Health Index - to which scientists globally contribute their findings. The global score of ocean health was only about 60 out of 100 and more was known than ever about the impact of humans on the ocean.

"Fifty years ago, we didn't know that. We thought the ocean was too big to fail. What we do to the ocean, we do to ourselves. It affects the air that we breathe, the climate that we experience, the habitability of earth. By changing the ocean, we put ourselves at risk."

On top of the grim warnings and passion, she is also a realist. When dealing with those politicians, she also cannily points out tourism in areas where the ocean is healthy is a lucrative business. She points to Palau - a magnet for shark-spotters - or the Galapagos Islands by way of example. She estimates the value of the fish alive to the value of the fish dead in the Galapagos is 200 to one.

"Tourism far outweighs the value of fishing in most parts of the world, in terms of the dollars you get for it."

There are still expeditions she wants to go on.

Earle has lived below water for weeks at a time, most recently just a couple of weeks ago in Florida Keys, surprising the sea life at all hours of the day and night to see what it was up to. But she is a wee bit envious of film director James Cameron, because he has been to the one place that she most wants to visit: the deepest part of the ocean.

Only three people have ever been to that place, 11km underwater - Cameron went down to the Mariana Trench in a submersible in March this year, the first to do so since 1960 when Don Walsh and Jacques Piccard also dropped down the Mariana Trench.

Earle passed on her passion for the ocean to her children. She has three and all were taken along on expeditions as they grew up - all have swum with the whales and dolphins. "They are, in a way, like little marine mammals."

Her eldest daughter runs a company that organises equipment such as submarines for ocean exploration. Her son patrols the ocean for California Fish & Game. The youngest daughter - a musician - still dives and helps on Earle's expeditions.

As for Earle, she has no intention of growing out of her own ambition to explore.

"As long as I breathe, I expect to dive," she says - and should old age prevent her putting on flippers and a mask and scuba tank, there are still submarines to take her to the ocean floor.