How do you train an infant or young toddler to swim?

Question

I recently saw a video on Facebook (see it here on YouTube) that involved a young boy, approximately 18 months old, that literally dived into a pool, was fully submerged for at least 7 seconds, and kicked/swam his way to the surface of the water. At this point, he spends another 2 full minutes on his back, staying afloat and keeping his face out of the water. (A parent was in the pool, off-camera, the whole time. This was an educational/informational video.)

It also appeared to me that while the child was underwater he was covering his nose and/or mouth with one of his hands, and so returned to the surface using only his legs and one arm to swim.

I'd heard of babies being train to keep there heads afloat, and I know there's a reflex that causes them to hold there breaths when submerged. But, I'd never been under the impression that diving (practically head first!) was part of that training?

What are the safe techniques used to train such a young child in that way?
What type of background or certifications should you look for in an infant swim instruct to achieve this?
How much in-the-water time does it take to teach young ones this particular skill?

Here are some stills from the video, which illustrate the type of techniques I'm asking about:

Answer 1

My baby girl who is now almost 2.5 years old have been taking "swimming" lessons since she's 3 months old. We bring her to a private pool in the surroundings each Saturday and she gets a private lesson during 15 minutes, without us being in the pool.

In the beginning, the goal is "survival": teach the baby to fall in the water from various heights in various positions (sitting on the poolside, head first, ...) and recover a safe position, on her back, floating for at least 4 minutes. The lenght this takes dpends on the child, from a few months to a year the teacher said. It took my girl 6 months I think to get her "diploma". Then the process slowly evolves towards what begins to look like swimming movements, but as baby this age don't master all of this nor understand everything they're told to do, this is basically a very repetitive training.

Here are some videos of her during the lessons. The older ones, at the bottom, show some examples of various exercises in the "survival phase". The newer ones, to the top, show some examples of exercices of "real" swimming.

Note that the teacher (and his wife on some videos) has several years of experience with babies, this pool was created by his father who was also teaching kids to swim and is very renowned around here so I didn't look for any other "qualification", which would anyway be useless to you as I live in Belgium :-) I say this because this is definitely not something we could have taught her ourselves, you need a lot of experience to know what to do and when the baby is ready to go further in the "cursus". We are very glad we took her to those lessons, she's really enjoying it, it could be a lifesaver, and it's anyway great to be able to play in the pool with your child on occasions without her crying all the time because her face is wet or so :-)