For generations of schoolchildren, the diving board symbolized the delicious freedom of summer vacation. With no homework to distract, riotous chatter coalesced around diving towers in swimming pools. An impressive leap might be a means through which a swimmer could flirt or assert social standing. But for others, the magic was simply in the exhilarating, even transcendental free-fall into the shimmering blue. How often can a kid experience that?

Today, municipal diving boards are increasingly hard to find. Like many everyday activities, when a dive goes wrong, it can be fatal. And so since the 1970s, health and safety concerns, lack of investment and new diving regulations have led to a decline in the amateur pastime. As of 2015, there are just three public pools in New York City with ...