A veteran marine biologist is hopeful the Great Barrier Reef can return to its former glory within a decade after witnessing a spectacular coral spawning event dubbed the "Everest of reproduction".
Gareth Phillips has led an eight-strong crew off the far north Queensland coast to monitor the event which occurs along the 2600km reef annually.
In a spawning event, coral project trillions of sperm and eggs for fertilisation in what Mr Phillips describes as "an explosion of colour".
Mr Phillips likened the new coral life as a reflection of Australia emerging from COVID restrictions.
"Nothing makes people happier than new life - and coral spawning is the world's biggest proof of that," he said.
"We are coming out of restrictions with a fresh leap of life just as the reef is spawning. That positivity is what people are feeling. It's the celebration of the year.
"I've seen the corals all go off at once, but this time there seemed to be different species spawning in waves, one after the other.
"The conditions were magical with the water like glass and beautiful light coming from the moon."
The team of six divers, at Point Break on the outer edge of Flynn Reef about 60km east of Cairns, each ventured out to different coral as they erupted through the night.
"About five different genus of Acropora, the branching corals, went off releasing mauve-pink parcels. Next, the Porites, the big boulder corals all started smoking at once releasing what looked like a river flood plume turning the water cloudy," said Mr Phillips.
Coral species spawn on different nights, with some events lasting up to three hours.
Mr Phillips - who has 20 years' experience and researched the reef for a decade - says responses like this give reseachers hope for its regrowth.
"It is like an annual stocktake of what species are spawning," Mr Phillips told AAP.
"It's the Everest of reproduction in nature.
"It is a magical experience to see big boulder corals smoking as they release their spawn or beautiful soft coral spaghetti waving and releasing tiny pink balls."
Research released this month painted a grim picture for the world's largest coral reef system.
A James Cook University study found less than two per cent of the system's coral reefs had escaped bleaching - caused by rising ocean temperatures - since 1998.
But Mr Phillips said the spawning event would renew hopes the reef could flourish again.
"Coral spawning is a sign that the ecological process that sustains reefs is still intact," he said.
"If we get some spawning, or lots of it, it is a sign that there is recovery underway, that the system is working.
"It (reef) has got a lot of pressures, we are not denying that, but it (spawning) can give us reassurance that the reef is recovering."
Asked if it could return to the healthy reefs that were prevalent before 1998, Mr Phillips said: "It is possible as long as there is no more disturbances, heat waves and things like that."
"The reef is huge, it is made up of 70 unique regions. It is hard to give it one diagnosis - it may impact on one area but others may recover," he said.
The expedition has been funded by Tourism and Events Queensland, Tourism Tropical North Queensland and Tourism Australia.