That is so great your babies are demonstrating their water-comfort!! Encourage it while it's ready accessible. It is very natural and easy for infants to learn to swim. Waiting until they're 3, 4, or older is harder on the child.
My mother was an infant swim teacher for 15 years. She swore that WITHOUT meeting the child, my mother could tell you on the first day which children would learn to swim and which ones wouldn't -- simply by observing the mother.
The "trick" to teaching babies to swim was to separate them from their mommies ASAP. The instructors tells 20 mommies to stand in the pool in a large circle, and they'd "pass" their baby to the mommy on the right. That baby would get one ineffective pass from his own mom, and 19 effective passes from the other mommies, before he got back to the start. Nervous mothers who were sure their baby "hated having water in his eyes" would be amazed at how receptive and happy their child was once he was in someone elses arms.
Every dunk underwater receives hugs, effusive praise and encouragement. Mothers are taught to never show concern or nervousness, or even sympathy, because babies immediately pick up on the fact that if mommy is worried then something must be
scary
. That is incorrect and counterproductive. If a baby is unhappy about floating on her back, the teacher would take the baby, and keep her floating and moving until she stops fussing, all the while repeating "good job, you're fine, you're safe, you're doing great, you're okay, good job!" Tone of voice is everything. As long as you don't reward fear by validating it, they're fine.
There are still some real swim schools out there, but they're harder and harder to find, as more people are willing to forgo real swim lessons in favor of "water play time".
I was fortunate to have this class. My brothers and I were diving off the meter board and swimming to the side of the pool - using front crawl - at
18-22 months old. We were diving for sinkers in 8 feet of water at 2 years old. I was on the diving team at 5 years old.
My own children started their swimming lessons at 12 weeks old. My daughter was asked to join the elementary school swim team when she was three years old! (However, I declined.)
