The internet is full of videos of tiny tots "swimming" under the water -- even smiling and looking around while they're doing it. Is it really possible for very young babies to learn to swim. And should they?

The technique is called Infant Swimming Resource (ISR), and it teaches children as young as six months old how to "self rescue."

Keri Morrison of Palm Beach Gardens, Florida, had to defend herself in May after a viral video of her infant struggling while learning to swim drew criticism from people who felt the lesson was too extreme for a baby.

A past tragedy was propelling Morrison's efforts, however. Jake, her two-and-a-half-year-old son, drowned three years ago after slipping out of the house in the dark and falling off a dock.

"I wish I could go back in time and put my son in these lessons," Morrison told the "Today" show, as she teared up. "I'm pretty confident he would be here, and as a parent, I felt like I failed my son. And I was just determined that was not going to happen with my daughters."

In the video, her tiny daughter is lured by an adult in the water, and then flops face-first into the water before eventually -- after an agonizing struggle -- flipping onto her back unassisted.

"I couldn't finish the video. It made my heart sink," wrote one Facebook user.

The technique is called Infant Swimming Resource (ISR), and it teaches children as young as six months old to "self rescue." In lessons five days a week, in 10-minute sessions for four to six weeks, babies learn to right themselves after being facedown underwater.

As for a baby learning to swim through ISR, Bea Skeens, a recently retired swim teacher in Cumming, Georgia, is skeptical.

"I don't believe in it," she said. "A baby that young cannot actually 'swim.' No matter what you do, you cannot predict every situation, and there is no guarantee [even with ISR] of a child surviving. But that doesn't mean a parent should not start preparing a child for this skill as soon as his first bath."

She added, "For people who have pools, once the baby can walk and open a door, there is a danger of that child falling into a pool. By then, one hopes parents have taught the child to hold his breath."

Skeens taught swim lessons for years through her private business. While infants are naturally unafraid of the water, she said children can develop a fear of water from their parents -- who are afraid that something will happen to them from their own previous experience.

"The least effective technique is to teach the baby to blow bubbles," warned one former swim teacher.

"If you put a young baby under the water, she will not swallow water and will naturally move her arms and legs," Skeens told LifeZette. "I don't think you can call that 'swimming,' but some people will, even though the baby doesn't go anywhere."

From the very first bath, pour water over the baby's face, said Skeens, to get the child used to the sensation. Have the baby's body in the water, holding the baby in the back float position or using the neck ring, or holding the baby's head. On the belly, hold baby under the arms and on the chest. Obviously, a parent must never, ever leave a child alone or unsupervised anywhere near even the smallest amount of water.

"Teach babies to be comfortable in and under the water, so that as they grow they will be able to and want to learn to swim," she advised. "Most children will be able to propel themselves to safety by two years old -- even if just to turn around and catch the wall if they fall into a pool."

Drowning is the leading cause of unintended, injury-related death for children ages 1 to 4 and the second-leading cause for children ages 1 to 14, according to the World Waterpark Association. Taking formal swim lessons can decrease the incidence of drowning by 88 percent in kids ages 1-4, the association notes.

"The least effective technique is to teach the baby to blow bubbles," warned Skeens. "Babies will hold their breath while under the water -- children can hold their breath for up to two minutes. Most children who drown are found within that time frame. Blowing bubbles is for three- and four-year-olds."

"Make sure that you don't just dribble the water -- you have to pour the water over his face and play and laugh and smile."

One of the biggest obstacles to a child's comfort and proficiency in the water is inconsistent exposure to it. Many parents take their young children to swim lessons only in the summer -- and they have to start over each summer because the child forgets what he or she learned, she noted.

"I believe that what they do remember from the previous year is that they had very little control in the water, and they're therefore understandably hesitant to get in," she said. "I teach games and tricks to get children ages two to four in the water. After age four, they won't forget what they've learned. It's why the Red Cross does not recommend lessons until this age."

A video on Skeen's blog learntoswimwithmissbea.blogspot.com shows her then three-month-old grandson gliding happily underwater -- with his watchful grandmother holding him as he explores.

"If you want your baby to continue to hold his breath underwater, you need to take your baby to the pool and submerge your baby every two or three weeks -- or at least once a month. Also, don't forget to pour water down your baby's face in the bathtub. Make sure that you don't just dribble the water -- you have to pour the water over his face and play and laugh and smile. Don't stop and wipe his face or clear his face. Just continue having fun -- just as if you were in the pool."