Marine researchers from the NOAA recently documented the biggest Porites coral in the world in the Mariana Islands. The large coral, which is located in the Muag Islands in the Mariana archipelago, was studied by scientists as part of a wider project called the 2025 National Coral Reef Monitoring Program.

“This coral was so big, we actually couldn’t easily measure it due to dive safety restrictions,” said Thomas Oliver, PhD, a chief scientist of NOAA’s National Coral Reef Monitoring Program, in a statement.

The results of the study indicate that the stony coral spans 14,000 square feet (1,347 square meters) and is more than 100 feet (31 meters) across the top. The bottom also measures 200 feet (62 meters), making it the largest Porites coral ever discovered.

The newly discovered coral is 3.4 times bigger than the Porites colony discovered in American Samoa in 2020. Researchers also believe that it could be one of the oldest corals, estimating that it could be more than 2,050 years old.

“It is difficult to tell the true age of this coral because it doesn’t produce growth bands like other corals,” said Hannah Barkley, PhD, a chief scientist of NOAA’s National Coral Reef Monitoring Program. “We roughly estimate that Porites rus grows outward about a centimeter per year, so one could imagine that a colony of that size is pretty old.”

The site of the coral is located within the Mariana Trench Marine National Monument, which is a volcanic caldera that features carbon dioxide vents. This can create more acidic ocean conditions, helping scientists measure the impact of ocean acidification.

“It is remarkable to see both these extremes — a resilient and thriving mega coral, and a dead zone near the carbon dioxide vents — in the same area. Maug is truly such a special place,” said Barkley.