Credit: Seth Casteel/TandemStock.com

Seth Casteel knows how to bring out a dog's wild side. The pet photographer has snapped surreal photos of more than 60 dogs swimming underwater and diving into pools to chase after a coveted tennis ball or squeaky toy.

"I'm interested in photographing dogs in their element," he said. "I'm drawn to dogs because they share a similar range of emotions that people have. My whole goal is to tell a story and portray their emotions on their terms. I want them to be themselves."

Casteel's underwater dog photos were posted on the social news site Reddit.com last week and they became an instant viral hit, collecting thousands of likes on Facebook. Traffic to his Little Friends Lifestyle Pet Photography website jumped from around 200 visitors a day to more than 100,000 a day, he said, overloading his server. He said he's received thousands of emails and over 1,000 inquiries for private shoots from clients in 20 countries.

"It is crazy," said the 31-year-old who bounces between Los Angeles and Chicago for his work. "I'm like, what is even going on right now."

PHOTOS: See More Dogs Underwater

Casteel is an "underwater dog whisperer" if you will. He turned to pet photography full time about four years ago and has mastered the art of coaxing  four-legged subjects to get the shot.

"Most of the dogs I work with have never gone underwater until they met me," he said. "All the dogs in the photographs have voluntarily gone into the water and under the water. They are choosing to do this. We're all having fun along the way."

"We're teammates," he added. "It's a ball. Literally."

So what does it take to get that perfect shot of raw animal instinct or a goofy pooch bracing himself for impact? He won't reveal his secret exactly, but it's a game between Casteel and the soon-to-be paddling pooch.

"It could be a tennis ball, it could be something else," he said. "We start to play a game in the water. In the course of playing these games that I've designed, we get the photos."

Casteel has two dogs of his own - Nala, a mini Labradoodle he adopted from an animal shelter, and Fritz, a Norwich Terrier. Ironically, his two dogs are not big fans of the water.

"Nala doesn't like the water because she gets ear infections. Little Fritz, he's just high maintenance," Casteel said. "I wish I had a dog that liked to swim with me, but they're my pals."

He also likes cats, but has never photographed a feline underwater. "Cats aren't big fans of water. Cats are different challenge with photography. I like that challenge too."

Casteel thinks his photos have resonated because they showcase dogs at their best.

"It all has to do with emotion and expression," he said. "People are interested in these photos because they show a side of dogs that haven't seen before.

"People spoil their pets with the best care and attention and food and treats and toys…but at the heart of it, dogs still do have a wild side. I think they appreciate being spoiled, but I also think they appreciate the opportunity to explore their wild side."