NORTHBRIDGE — More than 100 people sat in absolute darkness in the Singh Performing Arts Center at Alternatives Unlimited.

And yet the light National Geographic underwater photographer- journalist Brian Skerry shed on what goes on under the ocean surface was like a klieg explosion.

There were two sides to what the 47-year-old Uxbridge native conveyed in an intense hour-long lecture Thursday, Aug. 27, at the invitation of Alternatives.

One was of the sheer awesomeness, mystery and beauty that lie beneath the surface of the ocean.

The other was of the terror mankind wreaks in the destruction of myriad species.

If it were just big fish eating little fish, William Butler Yeats’ "A terrible beauty is born" might apply.

But the message Skerry delivered about what man is doing in directly exterminating species as well as laying down an invisible, molecular plastic net that slowly poisons aquatic wildlife was truly frightening.

At the same time, Skerry sees himself as a messenger of inspiring individual commitment.

For example, he so emphasized the bad things that were happening to the shrimp population that a friend whose favorite dish had been shrimp not only stopped eating it but lectured a restaurant owner on the subject

The exultation in the creation and the sadness at what man is doing to it was accompanied by a third element.

Brian Skerry is a local boy who made good in a big way.

In interviews he still expresses amazement that a kid from Uxbridge could have succeeded the way he has. There is nothing boastful about it. If anything, it is an echo of what everyone around here who meets him must feel, that someone nobody knew as a prodigy of sorts taking super math and physics courses at, say, M.I.T., but going on from the Uxbridge High class of 1979 to Worcester State College, should have become someone with an impact on how up to 50 million readers of the National Geographic see and think about the world beneath the surface glitter of the ocean.

A photojournalist, Skerry specializes in marine wildlife and underwater environments. Since 1998 he has been an assignment photographer for National Geographic magazine. That means his "backyard" has literally become the whole planet.

One of the things others comment on about Skerry is his ability to go after subjects of astonishing diversity. He usually spends eight months of each year in the field. In any given year he may find himself in environments of wide contrast — from tropical coral reefs to diving beneath Arctic ice. He has lived on the floor of the sea, spent months on fishing boats and moved around in everything from snowmobiles to canoes to helicopters to get near the subject of a photograph. Skerry estimates he has spent more than 15,000 hours underwater over the last 30 years. Uxbridge native Brian Skerry was in town last week to discuss his underwater photography and his passion for the sea.

At the Singh Center, Skerry joked that he and his wife once attended a divers’ exhibit in Boston but that his wife had wanted to go to a flower show instead.

"If I had listened to her," he said, "I might have become a florist."

For National Geographic, Skerry has done a wide range of photojournalism, from the harp seal’s challenge for survival in the frozen waters of the St. Lawrence River to the dramatic diminution in the world’s fisheries. He has also written about and photographed the planet's only remaining pristine coral reefs, the dwindling number of right whales, the alarming elimination of sharks, marine reserves, sea turtles and squid.

Skerry has also worked for or had images featured in magazines like People, Sports Illustrated, U.S. News, BBC Wildlife, Smithsonian, Playboy, Esquire, Audubon, Outdoor Life, GEO, Maxim, and Men’s Journal, as well as in countless publications worldwide. He is also the author/photographer of three books.

Skerry has lectured on photography and marine conservation issues at venues such as Harvard University, The National Press Club in Washington, D.C., and the Royal Geographical Society in London. He has also appeared on television programs such as ABC’s "20/20" and "Good Morning America." Among the organizations he belongs to are the ILCP (International League of Conservation Photographers), The Boston Sea Rovers and The Explorer’s Club. He is also on the Board of Overseers of the New England Aquarium and was just last week named the New England Aquarium’s Explorer In Residence.

In one interview, Skerry said: "The oceans are in trouble. There are some serious problems out there that I believe are not clear to many people. My hope is to continually find new ways of creating images and stories that both celebrate the sea yet also highlight environmental problems. Photography can be a powerful instrument for change."

In another interview, by A.J. Baime, Skerry spoke of his dream growing up in Uxbridge of becoming a National Geographic photographer. "It was a slow evolution," he said. "There were a lot of days when I could've packed it in." "The odds were against me, a billion to one," he said, "that a kid from Uxbridge could make it in this business. But I kept doing it."

"He's ‘shot’ swordfish off Italy, killer whales in the Norwegian Arctic, sperm whales off the Azores. He's taken pictures of sea cucumbers, anemones, ship wrecks, and more than two dozen kinds of shark, including blues in New England and great whites off Australia. ‘No matter how much time you've logged underwater, a great white is incredibly intimidating,’ he said. ‘Their presence overwhelms you.’"

In another extended interview, Skerry said he "was drawn to the water from a very young age and was always fascinated by ocean documentaries. I'd have to say however, that the movies ‘Jaws’ and ‘The Deep’ (1975 and 1977) actually made me get certified, though. I suppose most people were scared out of the water by ‘Jaws,’ but it made me want to see sharks even more. I wanted to be Hooper!"

Asked what he was proudest of, Skerry mentioned his work photographing shipwrecks early in his career. He said he was fortunate to dive with some great divers on some challenging sites such as the Andrea Doria and other wrecks.

He also said he has been most pleased with the photo work he has been doing since 1998 for National Geographic. With the support of The Geographic, he said, he has been able to plan and photograph stories on subjects of great interest to him — "from natural history subjects such as harp seals, squid and sharks to stories about major environmental issues."

Asked about any pre-dive routines he has, Skerry said he usually tries to look over all of his gear, just to make sure everything is in good shape prior to a dive.

"I often open the tank valve, putting pressure to the regulator when I first get on the boat, allowing the hoses to sit with pressure in them for the ride out to the dive site," he said. "If something is going to blow I'd prefer it happens on the boat!"

To find out more about Brian Skerry and his work, the reader may contact his Website http://www.brianskerry.com