Most instructors and students have no idea of the powerful forces of water in waves, currents, or temperatures.  Most people including instructors are unfamiliar with risks swimming in unfamiliar places.  As a result people tend to overestimate their swimming ability.  That is the #1 reason why people unintentionally drown.  On average there are ten each day.  Two are children generally under age 4.  But the other eight are adults who probably never learned to master their floating and breathing skills to survive in water over their heads.

I've learned that when you understand the need to learn to swim you'll be more motivated to learn correctly to master floating, streamlining to be efficient, breathing to swim farther with less effort, and avoid risks.