They say time and tide wait for no man, and it's safe to say that few people understand this truism as well as diver and explorer Dr. Greg Stone, one of 12 individuals recently named a National Geographic Adventure Hero of 2006.

The December issue of National Geographic Adventure magazine describes the heroes as "12 people who dared to dream big," but in Stone's case this is something of an understatement.

Stone is more than a dreamer. He is a marine biologist and an adventurer, and he is the big heart and busy hands behind the creation of the Phoenix Islands Protected Area established last March by the government of Kiribati. The Republic of Kiribati comprises 33 islands located near the equator halfway between Hawaii and Fiji in the Pacific Ocean. The preserve itself covers 184,000 square kilometers, the third largest sanctuary for marine wildlife on the planet. Stone has an office job, too, as vice president for Global Marine Programs at the New England Aquarium in Boston, but with a full beard, tousled hair and year-round tan, he looks much more like a weathered mariner than an experienced administrator.

Trained as a marine biologist, Stone has spent decades studying the oceans in an effort to document their mysteries and protect their biological health and wealth. He has spent days on end living in an underwater research station off the coast of Bermuda, traveled to a depth of 6,000 meters in a Japanese submersible and logged thousands of dives. He has also led several prominent expeditions, including an international team that recently dove in the waters off Thailand to assess the impact of the 2005 tsunami on coral reefs.

In 2000, he was co-leader of a scientific team that tracked the largest known iceberg in history through the seas of Antarctica, and the book he wrote about that trip, "Ice Island," won the 2003 National Outdoor Book Award for Nature and the Environment.

To date, however, the highlight of his career was last March in Sao Paolo, when he and a Kiribati government delegation announced the creation of the Phoenix Islands protected area.

"That was a milestone for me, the culmination of five years of work. It was deeply gratifying," he said by e-mail last week.

Stone, 49, and his wife, Austen, have been family friends for years, but catching them at home in Boston can be touch and go, since they are often in New Zealand doing long-term research on endangered Hector's dolphins, or just about anywhere else on the planet. So, when the New England Aquarium press release arrived, announcing Stone's National Geographic Hero award, I was brought up to date on the Kiribati project.

"At his first underwater glimpse of the coral reefs of the Phoenix Islands, Stone realized that they were among the most pristine coral reefs in the world. His second thought was that this stunningly beautiful and important ecosystem in the south central Pacific must somehow be protected," explains the press release. It goes on to explain that Stone was "the driving force" in the effort to create the marine wildlife sanctuary.

"It's the most magnificent atoll marine wilderness area I've ever seen," Stone told me. "The islands have experienced little human impact."

But forging an agreement to protect the area was far from easy. It took years of preparation and required Stone to draw on his skills as an oceanographer, diplomat, expedition organizer and fundraiser.

He began by building relationships with the local people and the government officials of Kiribati. Next, he and his colleagues started to document the amazing abundance of marine life around the islands. After three expeditions and 1,500 dives, Stone and his colleagues had documented hundreds of species of marine life, including several never before seen species of fish and coral.

Taking a close look at paradise revealed commercial fishing was beginning to take its toll on the region. The government of Kiribati was interested in protecting the near-pristine coral reefs, but they were also concerned because protection would mean restrictions on commercial fishing, and this would result in lost revenue, money Kiribati would normally get from issuing foreign commercial fishing licenses.

So the next challenge was money. Stone, with the help of Conservation International's Global Conservation Fund, designed a unique endowment fund that would provide revenue to the Kiribati government in lieu of lost fishing license fees and also provide income to operate and protect the sanctuary. Supporters of the fund came from around the world and included the Oak Foundation, the Pew Charitable Trusts, and the Akiko Shiraki Dynner Fund for Ocean Exploration and Conservation.

Stone responded with predictable modesty when quizzed about the National Geographic Hero honor. "It means a lot that the attention focuses people on the issues," he said. "Especially, in this case, protecting the oceans."

Over the years, I've heard a lot of Stone's stories and they need no exaggeration. Crashing through Antarctic waters or traveling thousands of meters deep in a submersible warrants no embellishment to make it sound hair-raising. He told me a story last week when I asked him to recount a scary moment in his adventuring.

"Scary? Probably the day I was diving in the Ross Sea [along the coast of Antarctica] alongside an iceberg and the cold down currents began pulling me and my dive partner into the depths," he wrote. "We swam horizontally away from the berg and got out of the current, but at the time the sea floor was 5,000 feet [1,500 meters] down so we were over very deep and in freezing cold water."

Next time we're having beers I have to ask him if these guys ever wet their diving suits.

Stone knows the risks and accepts them for very simple reasons. "My love and passion for the oceans and the joy of knowing they are a little better off from my work," he said.

It's a love he's had for decades. As a child he used to sit on the family couch and watch Jacque Cousteau television specials, while wearing his flippers, snorkel and mask.

"I learned to scuba dive the day I turned 16," he recalls. "I've been obsessed with the ocean ever since."

So I remain optimistic, too, knowing that there are heroes like Stone committed to risking personal safety in order to save our planet.

His is a truly magnificent obsession.