The difference between and baby and a puppy.
Here's our dog, Bella, as a puppy!
Submerging babies beneath the water has been the norm for years now. It's been sold to us parents as the way to get a child swimming, and it's standard practice - many baby swimming teachers wouldn't dream of teaching a class without at least one conditioned submersion. And it's fair to say that submersions really don't put every baby off - even if your baby has been frightened by submersions in the past, a few terms of less high-pressure classes can usually help them with any worries they have built up.
When I was initially trained as a parent and child teacher, I was taught to show parents how to submerge their child, but it never felt right. The thing I could never get on board with was the underlying psychology. Parents are taught to give their child a verbal cue before putting them beneath the water - so you are essentially training the baby to associate the command with the action of being submerged. This is called conditioning - you're creating a learned association. When we train a puppy to sit, or do a trick, we are pretty much doing the same thing - linking a command and an action. But babies are far more intelligent than puppies, as we well know!
The instructor will tell you not to submerge the baby if they show signs of distress, but that can be open to interpretation - and if the parent or teacher are feeling under pressure, or if they see submersion as the only route to swimming, they are less likely to pick up on the baby's cues. Likewise, you are taught to expect one of a list of reactions from the baby - they might be frightened, or startled - or they might not mind a bit. But why should they be put in that position in the first place?
Babies are proper people from the word go - with thoughts and feelings and opinions. if we condition babies, are we really treating them with the respect they deserve?
There really is another way - you can teach your baby to swim without an adult putting them beneath the water once, and they end up as confident, strong little swimmers as a result. Babies don't need conditioning - and if they don't react well to going under water, the problem is with the teaching technique and the enforced submersion, not with the baby himself.