At 1,640 feet (500 meters), the gigantic detached reef stands taller than the 1,250-foot-tall (381-meter) Empire State Building.
Researchers with the Schmidt Ocean Institute made the surprising discovery on October 20 while mapping the seafloor of the northern Great Barrier Reef.
At the crest of the reef, where the blade-like structure measures 984 feet (300 meters) by 164 feet (50 meters), the team spotted lots of fish, including sharks, as ABC (Australian Broadcasting Corporation) reports.
“To find a new half-a-kilometer tall reef in the offshore Cape York area of the well-recognized Great Barrier Reef shows how mysterious the world is just beyond our coastline,†said Jyotika Virmani, executive director of Schmidt Ocean Institute, in its statement.
In the past year alone, researchers with the Schmidt Ocean Institute have made a host of intriguing new finds, including a 148-foot-long (45-meter) siphonophore, several undescribed species of black coral and sponges, and upwards of 30 new species.