Mum and Daughter Discover Coral Giant on Great Barrier Reef That Could Be World’s Largest
A mother and daughter taking part in a citizen science census have located an enormous coral colony off the Great Barrier Reef. The find, measured at roughly 111 metres in maximum length and covering thousands of square metres, is being treated as one of the most significant reef structures recorded and may be the largest documented colony on the reef.
Discovery by Jan Pope and Sophie Kalkowski-Pope
Jan Pope first encountered the formation while scuba diving on an uncharted section of reef a few hours offshore from Cairns. Late last year she returned with her daughter, Sophie Kalkowski-Pope, and the two documented the site again a fortnight later. Both women are experienced divers and underwater photographers; Pope has been diving the Great Barrier Reef for 35 years and the pair have been participating in the Great Reef Census for the past couple of years.
Coral identified as Pavona clavus and measured
Field measurements and mapping put the structure at about 111 metres in maximum length—roughly the length of a Premier League football pitch—and at an estimated area of 3, 973 square metres. That area was described as about half the size of a soccer field. Independent documentation of the site has also been expressed in imperial units as more than 40, 000 square feet. The colony has been identified as the coral species Pavona clavus, a type known for the capacity to form very large, hardy colonies.
Citizens of the Reef, Great Reef Census and robotics mapping
The discovery was made under the Great Reef Census, a community-based research project led by the conservation charity Citizens of the Reef that uses crowd-sourced images and volunteer surveys to monitor coral cover across the Great Barrier Reef. The organisation estimates it has surveyed a quarter of the reef since 2020. After the divers alerted the charity, teams returned with special cameras, underwater measurements and 3D computer modelling to map the formation. Serena Mou of the Queensland University of Technology Centre for Robotics helped measure the colony and said the mapping will allow teams to return in future months and years to make direct, one-to-one comparisons to understand how the formation changes over time.
Genetic testing, sampling and scientific uncertainty
Scientists have flagged two possibilities: the mapped structure could be a single colony that grew from one original polyp, or it could be multiple adjacent colonies that settled and coalesced as they expanded. Confirming which is true will require genetic testing. Kalkowski-Pope said that because of the formation's size researchers would need more than 300 individual samples taken across the structure to determine whether it is genetically a single organism.
Expert perspective from Dr Tom Bridge and bleaching risks
Dr Tom Bridge, curator of corals at the Queensland Museum and a senior lecturer at James Cook University, characterised Pavona clavus as an uncommon and "quite hard to find" coral, but one that can produce "really, really ridiculously huge colonies" where it occurs. He noted a broader pattern: very large coral colonies are becoming exceedingly rare because bleaching events are increasing both in severity and frequency. For colonies that are dozens or hundreds of years old, Bridge warned that the chances of escaping damaging bleaching conditions or being resilient enough to withstand hotter waters are diminishing.
Significance for the Great Barrier Reef and community science
The Great Barrier Reef covers about 130, 000 square miles—roughly half the size of Texas—and large portions remain unexplored, which helps explain how such a substantial formation went unnoticed until this census effort. Citizens of the Reef described the find as among the most significant coral structures ever recorded on the reef and the largest documented and mapped coral colony in the world. The discovery reinforces the role of community-based monitoring: the pair’s images and footage made it possible for scientists to map the structure and plan follow-up work. What makes this notable is that an encounter by volunteer divers has produced a priority site for long-term measurement and genetic study at a time when rising ocean temperatures make tracking and protecting resilient reef features more urgent.
The find has prompted a coordinated sequence of actions—local divers documenting the site, charity teams performing mapping, university robotics specialists producing 3D models, and planned genetic sampling—that together aim to determine the colony’s biological status and monitor its condition over time.
