The documentary “Chasing Coral,” which has its premiere on Netflix on Friday, July 14, opens, appropriately enough, with images of coral — formations in various shapes and sizes, all of them stunning, charged with an array of colors so vivid they seem to pulsate. Other formations are a uniform hybrid of purple, green and gray. This isn’t stealth coral, or coral donning camouflage. It’s dead coral. Which is a problem.

The first voice we hear is that of Richard Vevers, a longtime diver and ocean enthusiast. He recalls the years he spent at a London advertising agency, where he was good at his job, and how he became convinced that what he was doing there was trivial. He decided to apply the communication skills he learned in his professional life to his passion, and created a company that both surveyed the world’s oceans and created “virtual dives” using special cameras. The story of a company man who leaves the corporate world to devote his energies to something more groovy is not new. But Mr. Vevers was alarmed by something in his new line of work: coral “bleaching” and subsequent death, a phenomenon spurred by a two-degree rise in water temperature. The results are not just visually unpleasant, they’re ecologically catastrophic.

Mr. Vevers was not the first to notice. One climate scientist, who warned the world about coral bleaching in the early ’90s, recalls how he was dismissed as an alarmist. But Mr. Vevers was seized by the idea of documenting the phenomenon, which makes the movie a scientific suspense narrative, as a team devises the necessary equipment and sets out to reefs around the world to record the damage. If you’re unschooled in marine biology, you see a coral reef as an unusual form of plant life. It isn’t. It’s animal life, and the movie provides a cogent explanation of how coral works. The macro photography of coral polyps, thousands of which protrude from any given coral formation, yields imagery that is more awe-inspiringly peculiar than anything in sci-fi cinema. And yet this is part of our real world.

In its explanation of how coral feeds, and how other forms of sea life feed on or around coral, the movie imparts an understanding of how humans rely on coral as well. So we’re made to care about how much of it is dying — what’s at stake is much more than an eye-popping attraction for diving tourists.