“We have kids that are afraid of water,” said Mr. Timricht, 43, a solidly built, avuncular kayak instructor.

Like reading and writing, swimming is among the essential skills that the French Republic has pledged to make available to its citizens since the end of the 19th century.

According to local authorities in Marseille, an average 47 percent of children from the Quartiers Nords entering sixth grade fail a mandatory swimming test, compared with 27 percent in the rest of the city.

Most pools in France were constructed in the 1970s amid a nationwide effort to build hundreds of sports facilities. Many in Marseille have fallen into disuse; others are frequently closed for repairs.

To those who live in poorer neighborhoods, the lack of access to public pools reinforces the overall feeling that residents, most of them descendants of immigrants, are not entitled to the same rights as others in the city.