A Decade-Long Experiment Is Unlocking the Mysteries of the Ocean’s ‘Deep Reefs’

Palau is famous for its spectacular and rich coral reefs. But these divers were planning to descend past those sun-lit marine communities and down into a lesser-known twilight zone known as the “mesophotic coral ecosystem.”

Mesophotic essentially means “middle” and “light,” which is where these ecosystems are—not quite in the bright daylight, not quite in the profound darkness, but somewhere in between. For simplicity’s sake, we’ll call these communities, which range from some 30 meters to 150 meters below the…