THE critically endangered grey nurse shark is congregating in large numbers at Wolf Rock off Rainbow Beach with divers recently spotting up to 70 pregnant female sharks at a time.
James Nelson, who took over the lease of the unique dive site six months ago with two others, said Wolf Rock is the only known aggregation site for grey nurse sharks on Australia's eastern coast.
"We're just blown away really," he said.
"There might be only 1000-1500 of these sharks on the east coast.
"Nurse sharks are typically cooler water sharks but the female sharks come up here because the water temperatures are more conducive for the gestation of the baby."
Australia's east coast grey nurse shark population declined rapidly in the 1960s when they were hunted by spear fishermen.
Mr Nelson said in summer they were typically seeing groups of about 30 at at time, but recent numbers of groups of up to 70 have had marine scientists saying it is the largest group there has been at the site.
Queensland Parks and Wildlife Service shark researcher and senior conservation officer Carley Kilpatrick told ABC News there could be up to a couple of hundred sharks there that are not being seen all at one time.
She said while there is no evidence to suggest the population is increasing , the use of Wolf Rock as a gestation site was growing.
"The biodiversity and the biomass of species at this site is going through the roof to be honest," she said.
Mr Nelson said the site has really accelerated in marine animal numbers since it was made a green zone about a decade ago, with the no touch, no take rule.
"This dive site is legitimately one of, if not the best dive site in Australia," he said.
"We feel like we've stumbled across one of the premier dive spots in Australia, which we're really excited about."
"It's quite common to see a turtle, eagle ray and a shark in the same moment (at Wolf Rock), but that's quite unique in Australia, and even the world."
Mr Nelson said divers at Wolf Rock can get very close to the grey nurse sharks who are "as harmless as an animal can be."
He said the sharks sleep during the day, but like all sharks they have to keep moving to pass water over their gills.
"They cruise calmly and are very relaxed - if you don;t surprise them, you can get within touching distance."
"They are grabbers and swallow fish whole - so they won't eat anything that won't fit into their mouth."
Mr Nelson said divers have also been encountering multiple manta ray sightings almost every day as well as large Queensland gropers.