By Pat Heagney and Lucy Loram for ABC
Beneath the surface of the Pacific Ocean off Australia's east coast, record numbers of humpback whales are making their way south on their annual migration journey.
After commercial whaling from the late-1800s to 1960s "pushed them to the brink of extinction", experts believe the east Australian humpback whale population is now reaching record highs.
"We know that population has reached 40,000 or more," Wally Franklin from the Oceania Project said.
"We believe the numbers are now getting close to what we call carrying capacity, when the number of whales born equals the number of whales that die of natural causes each year."
Dr Franklin has researched humpback whales for more than 30 years.
He said the recovery of the mammal's population was "remarkable".
"The impact of commercial whaling on this population was devastating," he said.
"By the early 1960s, as a result of over-whaling in Antarctica and along the coastline of Australia and New Zealand, the population crashed.
"In the eastern Australian population, only 150 survived.
"All the whales we're having the privilege of enjoying in our whale watching tours today have descended from that group of whales and made a miraculous recovery over the last 30 odd years."
Dr Franklin said he was honoured to have witnessed the gentle giants return to glory.
"Over the last 30 years we have been able to watch, with a great deal of joy, the incredible recovery of the eastern Australian whales recovering at 10 percent per annum," he said.
"It's been an absolute joy of my career to be actually out in the field, and both observe and collect data on that remarkable recovery."
A 'pretty strong' season so far
The return of whale numbers has also driven a tourism boom in the whale watching capital of Hervey Bay.
"It's looking like it's been a pretty strong season so far," said Peter Lynch, owner operator of Blue Dolphin Marine Tours.
"We've actually had a really good number of whales come into the bay this year … there were days where there were whales as far as the eye could see across the bay."
Lynch hoped greater awareness of the humpback whales' recovery would continue to drive tourists to Hervey Bay.
"I think the biggest thing right now is protecting the oceans so the whales can continue to survive," he said.
"There's no point saving them from being harpooned if we can't save the environment."
Leigh Fischl travelled from Sydney with friends to see whales at Hervey Bay.
"We were really excited to come, I've always wanted to see the whales, they're just so peaceful and graceful," she said.
"I was surprised to see so many, we didn't realise we'd see so many mothers and pods but they were situated all around us."
Bev and John Winks travelled from Rubyvale in Queensland's Central Highlands to tick whale watching off their bucket list.
"It was breathtaking, quite profound actually," John Winks said.
"A once-in-a-lifetime experience," Bev Winks said.
Hopes for future research
Dr Franklin said although the larger population was a "really good sign", it certainly was not "all done with humpback whales", when it came to research and conservation.
"There's an incredible list of research questions we need to address and we're looking out deeply for any funding to support us getting stuck into those," he said.
"Now we've got a real group of whales to study for the next few decades, what a great future we have for whale research in this amazing part of the world in the Wide Bay region."
-This story was first published by ABC