I learn to swim after I entered college. It seems strange that someone who lives on an island does not learn to swim but I believe many people who live in Penang island all their live still do not know how to swim.
The first thing I learn about swimming is the fact that all of us have a natural buoyancy - we all float. However, the buoyancy differs from person to person. The lucky ones naturally float with either their nose or mouth above the water which allows them to learn to swim more easily. I float slightly below the water and have to hold my breath and need effort to push myself above water to get my breath.
The key thing about learning to swim is to get comfortable being in the water. It is terrifying for first timers, you are in an environment without a solid support and everything is moving. Every gesture and movement you make changes your position in the water. I felt out of control the first time I went in the pool and was told to float. It is very easy to panic. I guess that is why we read so many cases of drowning where the panicking victim drags their savior down with them.
It is very important to stay calm. Struggling and making uncontrolled movement could easily move us deeper into the water as well as zapping us of our strength. The key thing I learned about swimming is to preserve our strength - to relax until someone comes to rescue us.
Swimming is a survival skill, you never know when you need the skill!