"Surprising, Vibrant Reef Discovered in the Muddy Amazon"

"After sampling muddy water from the mouth of the Amazon River, oceanographer Patricia Yager steamed in the research ship Atlantis toward the continental shelf, where a Brazilian colleague was chasing a phantom. Yager’s colleague was carrying a 1977 six-page research paper that included a hand-drawn map suggesting this region might mask an extraordinary set of reefs.

Yager was skeptical. The mouth of the Amazon was thick with more runoff and sediment than any river in the world. She had heard diving in this area was like swimming through goopy, dark stew. "I thought that everything would have just been smothered by settling mud from the river's plume," she says.

But when her colleague, Rodrigo Moura of the Federal University of Rio de Janeiro, dredged small areas near the shelf that day in 2012, he uncovered one of the most surprising finds in modern sea research–an extensive deepwater reef system up to 120 kilometers offshore, below the Amazon's thick, dirty plume."

Craig Welch reports for National Geographic April 22, 2016.