Here, at the ancient necropolis of Nuri in Sudan’s northern desert, Kushite royals were laid to rest millennia ago in a series of underground burial chambers beneath mighty pyramids. Now the chambers were flooded with groundwater leaching from the nearby Nile. Archaeologist Pearce Paul Creasman, funded in part by a National Geographic Society grant, was leading a team that would be the first to attempt underwater archaeology below a pyramid. Initially, I’d been calm, even excited, about going along to photograph this ambitious and risky effort, in 2020. But as I walked deeper underground, my heart raced, and I could barely breathe.

I’d known this existential anxiety before. Nine years ago, from crouching in a drainage pipe