The creatures of the sea icome in all shapes and sizes, and Bill Curtsinger has been eyeball to eyeball with many of them.

Curtsinger is a renowned underwater photographer. His work can be found in leading natural history and environmental publications the world over. He is a major contributor to National Geographic, having produced more than 30 individual articles and five cover stories for the prestigious magazine.

Though he has conducted photographic diving expeditions in all the world’s oceans, Curtsinger is particularly fond of the waters of the Arctic and of the cooler, temperate zones of the North Atlantic off Maine, where he makes his home.

“I specialize in cold-water photography,” Curtsinger said during a recent interview at his studio in Yarmouth. “Everybody wants to dive the tropics and the coral reefs, but I’ve never been interested in that. I really enjoy diving in colder waters.”

Curtsinger said temperate waters are home to thousands of species ranging from microscopic phytoplankton and zooplankton to large mammals, such as seals and whales. He said the nutrients in the colder oceans enable creatures to thrive and they congregate in spectacular numbers. Swimming among them and taking their picture is what keeps him going.

“You’d be hard-pressed to find a commercially valuable species on a coral reef,” he said. “But go to the North Atlantic and you can find a huge biomass of species. That’s why the fishermen are out there, because that’s where the fish are.”

If it’s hard to imagine how a guy who studied photography at colleges in Arizona wound up thriving in the oceans of the world, it isn’t to Curtsinger.

“There are water persons and land persons, and I’m a water person,” he reasoned. “As a kid, I always had that water thing.”

To get fully submerged in the “water thing,” Curtsinger joined the Navy in 1966 and ended up as a member of its elite photo unit, the Atlantic Fleet Combat Camera Group. Curtsinger spent much of his hitch taking photos of underwater installations, ships and weapons. When his tour ended four years later, he knew he had found his life’s work.

“By the time I got out of that unit, I had a pretty good portfolio. I did my first National Geographic job that year; it was a piece on the Antarctic,” he said. “I’ve been hustling ever since. You always have to hustle, it’s the nature of this business.”

An underwater photo shoot is far different from one on land. It requires detailed planning and perseverance. Curtsinger said the very wildness of the ocean makes it difficult to find one’s subjects and to photograph them under the right conditions.

“You can’t arrange some of these moments, so you can go weeks without taking a single photo,” he said. “You’re just down there trying to maneuver your way into their world, to find yourself in an unobtrusive position, and those rare moments are few and far between. You don’t just walk out and do this. You need to know what you want to get, and then you have to know how go out and get them.”

Although Curtsinger uses “off the shelf” cameras for his work, their protective housings with external controls and lighting equipment are designed especially for underwater use. Even so, things can often go wrong, because lighting and water rarely go hand in hand.

“It’s the weakest part of the underwater system and it’s the single most frustrating thing to keep up with,” he said. “Underwater flash equipment is the hardest part of it.”

Curtsinger’s most recent assignment was to provide the microscopic photographs for the book “Sea Soup,” an educational science publication for children written by Portland author Mary Cerullo.

“Sea Soup” is published by Tilbury House in conjunction with the Gulf of Maine Aquarium. The book features stunning color photographs of phytoplankton that Curtsinger captured off the Maine coast last year.

Phytoplankton are microscopic plants that are found near the water surface. A tablespoon of water can hold millions of phytoplankton and Curtsinger said Maine’s Bigelow Laboratory has the largest collection of phytoplankton in the world.

The microscopic plants come in thousands of varieties and colors. Invisible to the naked eye, phytoplankton are the source of the planet’s atmosphere and climate and at the bottom of the ocean’s food chain. When the tiny plants bloom, they create a sea soup that provides sustenance for every creature in the ocean. Curtsinger has observed right whales swim through clouds of phytoplankton with their jaws agape, sucking them down like ice cream.

To take pictures of phytoplankton, Curtsinger used a special camera attached to a microscope and fabricated a strobe light to illuminate the minute plants. He is one of a few people in the world to use photomicroscopy for visual appeal. The photographs reproduced in “Sea Soup” depict a wide variety of phytoplankton in brilliant colors and odd shapes.

“Scientists take photos of these things to study them; they don’t take them to have them look pretty,” he said. “Phytoplankton has not really been done in a way that it can work its way into a high-quality magazine. I set out to photograph these little cells in a way where people would find the images intriguing and really enjoy looking at them.”

Before working on “Sea Soup,” Curtsinger spent a year roaming the North Atlantic photographing Atlantic salmon in their natural environment. His travels took him from Maine to New Brunswick, Labrador, Newfoundland, Quebec and the North Atlantic in pursuit of spawning salmon. He said the farther north he traveled, the more he encountered the salmon.

“We set out to do an Atlantic salmon story and we pretty much covered all the bases,” he recalled. “It was a story I always wanted to do, I had this moment and just decided to do it. I would lie in waterfalls while salmon jumped overhead. I also used a lot of remote cameras. I saw more salmon jump over a falls in the Humber River [in Newfoundland] in a day than ever return to the state of Maine in an entire year.”

Though he has been on diving expeditions all over the world, Curtsinger said that some of the best areas are right off the coast of Maine. He is particularly fond of the waters off Eastport, where the shelf drops off rapidly to a depth of several hundred feet. He said the waters there teem with aquatic life and the constant flushing by the Bay of Fundy tides makes every dive an adventure.

“I’ve gone down 200 feet and still haven’t seen the bottom,” Curtsinger said. “It’s a beautiful place but a difficult place to dive and you have to watch yourself. Once things go wrong, they can go wrong quite fast underwater. Underwater, that’s just the way it is. We don’t really belong there.”

Bill Curtsinger’s Web site is: www.billcurtsingerphoto.com. His latest books, “Sea Soup Phytoplankton” and “Sea Soup Zooplankton, written by Mary M. Cerullo, were published by Tilbury House and are available in Maine bookstores. He illustrated a feature story on Atlantic salmon scheduled to run in the April issue of Smithsonian.