As an expedition was exploring the waters around the Solomon Islands, its members spotted what looked like a shipwreck. Intrigued, they sent a diver down to investigate.
Summary
A National Geographic expedition near the Solomon Islands discovered the world’s largest coral, visible from space and estimated to be 300 years old.
The massive coral, the size of a blue whale, stores centuries of oceanic history and far surpasses the previous record-holder, “Big Momma,” in size.
Located in the Coral Sea, the Solomon Islands host remarkable coral diversity but face threats from climate change, including coral bleaching.
Scientists called the discovery a “beacon of hope,” showcasing the resilience of deeper-water corals despite global warming impacts.
This is ABC's fault rather than OPs, because the post title is the same as the article's, but it's not the largest coral reef. It's the largest individual coral.