"Underwater photography presents not only an endless world of creative opportunities, but also the chance to bring awareness to important causes such as water safety for children," explains photographer Seth Casteel to HuffPost UK Lifestyle.
Casteel adds that he was inspired to create the series after learning of the 'shocking' statistics around children and water-related accidents.
According to the Royal Society for the Prevention of Accidents an average of 40-50 children drown every year in the UK.
The babies in the pictures are being taught to 'self-rescue,' a technique which involves learning to hold their breath underwater, kick their feet, turn over to float on their backs and rest until help arrives.
Casteel said it was an exciting project to work on because his subjects, who ranged in age from four and a half months to 17 months, each brought something different to the shoot.
"All of the babies' reactions surprised me," he said. "It was impossible to predict what they might look like.
"One of my favourite images is of Michael R. [below] At 4.5 months old, he is the youngest baby in the book and mysteriously demonstrates such a unique confidence and wisdom while swimming."
"Younger swimmers were more co-operative and perhaps even more interested than older swimmers," Casteel adds. But I also met some spectacular older swimmers who had been swimming for months already.
"The biggest challenge I faced with the photography was the window of opportunity.
"Most of the babies only went underwater once or twice, and for just a second or two, so my opportunity to take pictures was extremely limited."
This isn't the first time Casteel has taken his camera underwater. In 2012 he released a book called Underwater Dogs, full of incredible shots like the ones in the gallery below:
"My first underwater project, Underwater Dogs, began as an unexpected series as I documented the lifestyle and personality of dogs and their connection with people and the water," Casteel explained.
"I discovered that water safety for pets was a topic that many pet owners were not very familiar with, which led to the Underwater Puppies book.
"Underwater Puppies is a celebration of puppies and the images are joyful, but the message is a serious one: We have a responsibility to keep our pets safe around the water, especially swimming pools.
"Through the course of exploring that topic, I became aware of the statistics regarding human children and water-related accidents and I was absolutely shocked."
"After experiencing infant swimming lessons and learning of the benefits, I felt that I could create images to promote this important cause of keeping our human children safe around water.
"I am not a father yet, but if one day I am, I'll definitely be signing up my baby for swimming lessons."
Underwater Babies by Seth Casteel is published by Headline, out now, priced £14.99.