AT age 77, American oceanographer and aquanaut Sylvia A. Earle is still diving, literally, and delving deep into the mysteries of the threatened oceans and their endangered creatures.

"No water, no life. No ocean, no us" is the message Dr Earle repeatedly conveys in her marine conservation efforts around the world, last month in Beijing in advance of World Oceans Day, which falls on yesterday. She spoke at an event sponsored by the National Geographic Society, the Oceana international oceans conservation organization, and La Mer cosmetics, which specializes in products using marine extracts. Earle herself is a marine botanist, specializing in seaweed, and is a consultant on the impact of oil spills on marine life.

Pioneering explorer, author and speaker about marine conservation, she said humans have caused more damaging changes in the oceans in 50 years than in preceding human history. The best diving spot in the ocean, she said, "is anywhere 50 years ago."

"The ocean is in trouble because of what we are doing to the ocean, what we are putting in the ocean and what we are taking out of the ocean," she said.

'Her Deepness'

Born in 1935 in New Jersey and growing up in Florida on the Gulf of Mexico, Earle was able to make ocean discoveries because of the huge leaps in science and technology. She has led more than 100 expeditions and logged more than 7,000 hours underwater,

Earle is an explorer-in-residence of the National Geographic Society. She was called "Her Deepness" by the New Yorker magazine and The New York Times, and named by Time magazine as its first "Hero for the Planet" in 1998.

Her most recent saturation dive was in July 2012. Last October, during her fourth visit to China, she dived in the South China Sea.

She will return to China in September to join exploration in the Sea Dragon submarine, the deepest diving submersible.

"It's easy to make new discoveries today," Earle told Shanghai Daily in an interview. "I'm really fortunate to have a ride with new technology that made access to the sea possible in ways not possible before the mid-20th century."

Earle made important discoveries about whales.

"When I began, no one knew that whales sing and make social sounds," she said. "Some whales have voices so powerful they can travel hundreds of miles."

Before Earle, no one had documented whales' vocalizing. She discovered that humpback whales spit circles of bubbles to encircle and trap shrimp and little fish.

"Now everyone can see this. Because access to the sea happened when I was young, I had a chance to be among the very first to discover this and be there to watch," she said.

According to Earle, only around 5 percent of the ocean floor has been seen by anybody, let alone explored.

Earle's first impression contact with the ocean came when she was three years old and a wave knocked her over. At first she was afraid. "But then I caught my breath and I realized it was really fun and exhilarating. I wanted to jump back in," she said.

"As a child, I did not have words for the excitement of seeing this vast space of water. You could hear the waves crashing like a roar, and then you could smell the difference in the air. Finally you go out and touch the ocean, and that was so exciting," she said.

What really holds her interest is the fact that the ocean is alive.

"It's not just rock, sand and water; it's a living system, every glass of water from the ocean is filled with life," she said. "You can't feel lonely in the ocean, you are surrounded by life all the time."

The ocean keeps the earth alive. Seawater evaporates into clouds and falls back as rain, the ocean regulates temperature, and drives climate and weather.

"We know that the ocean is important to whales, fish and coral reefs. But we are as dependent on the ocean as any creature that actually lives underwater. We are sea creatures, too," she said.

Her own mother was 81 years old when she began to dive in the Gulf of Mexico, Earle said.

"Maybe someday I will have to use only a submarine to explore, but I expect that as long as I can breathe, I will dive."

Think like fish

Earle urges people to "think like fish" and imagine what it must be like to live in water where you don't fall down. "I treat fish with respect," she said and warned against over-fishing with technology makes huge hauls possible.

"Fish can live a very long time. Some fish you see on the market can be 100 years old, many reproduce and grow very slowly. It takes a long time to restore fish stocks after we take them out of the ocean," she said.

Many sharks must be 20 years old before they can reproduce, she said, adding that 90 percent of sharks are gone because people want shark's fin soup, and 90 percent of the tuna are also gone.

"Eating shark means you've taken the creature out of the ocean and you not only harmed that creature, you changed the nature of the ocean," she said. "We have choices, and maybe we can choose to keep the fish alive in the ocean, instead of on our plate."

"We must have limits on how much wildlife we extract form the sea without harming the ocean," she said. "Give the ocean a break in terms of wildlife. We should care for the ocean as if our life depended on it, and it does."

Fishermen need compensation, however, for loss of livelihood if they cannot fish, she said. In some places, funds are raised to retrain fishermen. In some places, income is generated from wildlife tourism, such as whale and dolphin watching and visiting protected coral reefs.

"There is new wealth in tourism," she said, adding that "a whale may be worth more alive than dead because people pay to watch them for many decades." A typical whale-watching trip in Seattle, Washington, costs around US$75 per adult, and that adds up.

Exploring the ocean leads to taking care of it, Earle said, "because if you don't know, you don't care...

"The next 10 years will be the most important in the next 10,000 years because we have a chance to use the power of knowing and restore the ocean."

It's one thing to say the ocean is in trouble, but the real message is that everyone is in trouble, she observed.

"We know that we can alter the nature of nature - we have changed the planet. We didn't think it mattered when I was a child, but now that we know, we have a choice. We can continue to indulge old ways, but now we can choose a different way, knowing that what we put into the ocean matters, what we take out of the ocean matter. It matters to our future.

"We may think we have a long and prosperous future," Earle said, "but if we continue what we are doing, our fate is not prosperous."

About Sylvia A. Earle

Dr Sylvia A. Earle is a pioneer in oceanography, deep-sea exploration, marine conservation and the advancement of women in science.

In 1970, she led the first team of women aquanaut-researchers, living 50 feet underwater for two weeks off the US Virgin Islands during the Tektite Project. When they surfaced, they were give a ticker tape parade in New York.

In 1979, she walked untethered on the ocean floor, 1,250 feet below the surface off Oahu, Hawaii. She went lower than any woman before or since.

In 1986, Earle tied the world solo dive depth record in a submersible and set the record for women, going 1,000 meters deep in Deep Rover, a craft developed by her marine engineering company.