To swim is a good thing. To know what boyancy is and then knowing how to do it is a.different thing. Then to know how to dive and stay underwater is more different than all the others listed above.
There are people that knows how to perform all types of strokes when it comes to swimming. There are the beast stroke, the back stroke and so on. I don't know their name so I wouldn't want to call something that's isn't correct 😂
There are people that have been able to master diving if not in big oceans but in swimming pools and can stay in for a very long period of time swimming from one point to another without even coming out to breath.
Those people should I call them super humans for that which they do? Cause it's hard. To even hold your breath underwater for more than a minute is hard but they could do it for up to 3 minutes.
There are even some that knows how to turn over. Their legs being up top and their hands below them using their hands to walk in the water. They're just special and since not everyone can do it they're always admired for it.
Can you swim yourself? And what type of stroke do you know how to swim?
If you want to talk further, you could also share what experience you can never forger when it comes to swimming.