The Great Barrier Reef has become a surging tempest of sexual activity, with mass coral spawning underway. 

Veteran marine biologist Gareth Phillips has led an eight-strong crew off the far north Queensland coast to witness the spawning event dubbed the “Everest of reproduction”.

In the annual spawning events that occur along the 2,600km reef, coral eject trillions of sperm and eggs for fertilisation in what Mr Phillips describes as “an explosion of colour”.

Mr Phillips says it is similar to Australia emerging from COVID-19 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.”

Divers were able to swing between 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 across several nights, with some ejecting spawn for up to three hours.

Mr Phillips says the eruption gives researchers hope for the Reef’s 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.”

It comes after recent research painted a grim picture for the world’s largest coral reef system.

A James Cook University study this month 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 spawning is a hint that 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 has got a lot of pressures, we are not denying that, but it [spawning] can give us reassurance that the reef is recovering.”

The expedition was funded by Tourism and Events Queensland, Tourism Tropical North Queensland and Tourism Australia.