<p>When I went to high school, the high school had a swimming requirement. It was not particularly rigorous (basically, can you avoid drowning in the pool and swim across the pool?), but students who did not pass had to take beginning swimming as their PE (PE was required for the first two or three years, but student had a choice of sports or activities every half-semester, except that non-swimmers had to take beginning swimming).</p>
<p>Regarding floating in the water, better floating ability is one of the few advantages of having higher body fat. Very lean people tend to have to actively tread water or swim in order to float.</p>