Seth Casteel is making a splash with his underwater HD photography of dogs as they dive in after tennis balls. The results of his experiment have created an Internet sensation, with ball to ball coverage on blogs of all stripes, from ABC News to the Discovery Channel and throughout social media, primarily Facebook.

“I was photographing a little Cavalier King Charles Spaniel named Buster. We were meant to do an ‘on-land’ shoot in his backyard, but he decided he would play in the pool the entire time. Watching him jump in time after time after a sinking tennis ball, it occurred to me that I needed to see what that looked like,” explains Casteel. “I had no idea what to expect, but I just thought the results were so fascinating and fun.”

As the name of his business, Little Friends Photo, implies, Casteel specializes in pet photography. To say Casteel loves man’s best friend would be an understatement. Like photographers who specialize in human portraits, Casteel seeks to bring out the unique personality of each pet. Casteel’s experiment yields personality plus as determined dogs paddle their way to their play prey.

“From the water’s surface, it’s a simple exercise: a dog’s leap, a splash, and then a wet head surfacing with a ball, triumphant,” says Casteel. “But beneath the water is a chaotic ballet of bared teeth and bubbles, paddling paws, fur and ears billowing in the currents. From leaping lab to diving dachshund, the water is where a dog’s distinct personality shines through; some lounge in the current, paddling slowly, but others arch their bodies to cut through the water with the focus and determination of a shark.”

The timing of all this viral attention comes at a perfect time for Casteel, who is putting together a book to be released this fall called Underwater Dogs, which features 80 portraits of diving dogs, which Casteel says “gives playful and energetic testament to the rough-and-tumble joy that our dogs bring into our lives.”

Casteel also has an exhibition opening in Brazil this month, which will be followed over the summer here in the United States. The photographs are available at Casteel’s website as art prints up to five feet wide. “They look so cool when they are big,” says Casteel.