I've done nothing but diving and snorkeling for so long that I forgot how to swim.
I joined a gym recently and this morning I went to swim laps in their pool. I got in the pool, put on my goggles, put my face in the water and began to swim. Then I breathed.
Note that there was no head action between "put my face in the water" and "breathed." I stopped, stood up and coughed. Then I did it again. It took me a moment to realize what was happening. It was so natural to simply breathe while looking down that the entire swim was awkward and weird. I did a couple of laps and then bailed on that and went and used one of the stationary bikes.
Sigh. What a maroon!