I've been infatuated with blue whales since I was a child (who isn't?), so I was thrilled to watch Flip Nicklin, one of the preeminent whale photographers in the world, speak last night at National Geographic. The 61-year-old Nicklin was introduced to whales as a kid. He began by telling how his father, also a diver and underwater photographer, once rode a blue whale that was caught in a gill net (he later set it free, don't worry.) Since, then he's been traveling around the world, from Patagonia to Sri Lanka, in search of the largest animal ever to have lived on Earth. And sometimes they're not very easy to find. "I'm fairly deaf," Nicklin said, "so I'm glad the whales are big." Big is an understatement -- the modern-day dinosaurs can be up to 100 feet long and weigh 200 tons, and their hearts can weigh as much as an SUV. They eat krill almost exclusively, and sometimes up to four tons a day. On a recent expedition, he spent more than three weeks at sea, and saw only one blue whale for a total of about 15 minutes. He got five usable photographs, all taken during the same minute. "They're good at playing hide-and-seek," he joked. But sometimes they are quite literally under his nose. In one video he showed, a blue whale eyed him curiously -- from less than five feet away. And most recently, he traveled to Baja, where he saw more than 20 blue whales. The real treat of the evening was the photographs, Nicklin's stunning images of the long, thin, torpedo-shaped creatures. Many of the photos have an eery quality, the blue-grey skin of the whales glowing underwater. During the photo slideshow, the crowd would periodically coo in awe, myself included. One photo showed a blue whale singing into a hydrophone dangling in the water, like an underwater studio recording session. Another showed a floating blue that was killed by a ship strike, which is one of the main threats to the creatures. Blue whales are currently classified as endangered on the World Conservation Union (IUCN) Red List. When I asked how many blue whales there are in the world, Nicklin said, "at least 2,000 and we think their populations are increasing," but other estimates are between 5,000 and 12,000. As he put it, when it comes to our knowledge of blue whale populations and behavior, "We are just at the beginning." Another audience member asked if he had a son or daughter to carry on his legacy. "Yes," he said, "But I had to hire him." Paul Nicklen, no relation and spelled with an "e", is an up-and-coming ocean photographer for National Geographic who has collaborated with Nicklin. Flip Nicklin, it seems, has led a very charmed life. Check out more of Nicklin's photos of blue whales, and learn more about his conservation work at http://whaletrust.org.