Tropical North Queensland

Where to experience the phenomenon that is coral spawning

Each year, the world’s largest synchronised coral spawning event happens along the Great Barrier Reef. It looks like a gigantic underwater snowstorm – but what exactly is it? And more importantly… how can we go and see it?


It really is the biggest sex show on Earth. Once a year (though this is staggered along the length of the Great Barrier Reef) the corals of the reef all release eggs and sperm (spawn) into the water at the same time hoping they’ll join up and create lots of baby colonies of coral.

The biggest synchronised spawning events in the world happen on the Great Barrier Reef, and as voyeuristic humans, we love to watch. In this modern era of sustained coral bleaching, the interest in coral spawning has never been so high (scientists are studying the spawning process to see if the process changes when coral is affected by bleaching).


Ha, well, see that’s the interesting thing. No-one knows exactly. Sure, marine scientists can predict a rough timeframe, but they’re never going to put their house on an exact time and date.

Scientists at Townsville’s James Cook University only discovered the coral spawning phenomenon for the first time in 1981, so while research around it has developed since then, it’s still impossible to say exactly when it will occur. And therein lies the main problem for those who want to observe the phenomenon. “There’s often no indication tonight will be the night,” says marine biologist, Stuart Ireland. “It’s often not till you’re actually underwater 20 to 30 minutes before that we’ll know.”

Generally, coral spawning takes place between November and December in the northern Great Barrier Reef. This year marine researcher and spawning expert Gareth Phillips predicts the spawning will occur between November 26 and November 29. Most experts are predicting the spawning to occur after November’s full moon.

However, spawning happens later on the southern reaches of the reef – sometimes as late as January/February. This year most predictions have it occurring there between December 20 and December 25 (it could be a Merry Christmas for snorkellers and divers). It can also occur at different times depending on how far out on the Great Barrier Reef you travel.


Coral Spawning on the Great Barrier Reef | coral spawning

Photo by The Great Barrier Reef via FB

There are several environmental factors which affect when coral are likely to spawn, just shy of lighting candles and streaming Barry White:

  1. The ocean temperatures must be 26 degrees or above for the month before for the eggs to mature enough.
  2. The coral will reproduce three to six nights after the full moon in November or December (in the northern Great Barrier Reef) when there’s less tidal movement.
  3. Spawning is also most likely to take place at least three hours after sunset when all plankton feeders are sleeping, giving eggs more time to settle into the safety of the reef.


Tusa Dive | coral spawningLast year coral spawning occurred between Heron Island to the south, and Port Douglas to the north, across a distance of 1000kms.

If you want to be amongst the action, your best chance of seeing coral spawning is by taking a liveaboard dive boat out of Cairns, because that’s where the highest concentration of dive boats on the Great Barrier Reef are. “I’d take a seven-day live-aboard if you want to have the most chance of seeing the spawning,” Phillips says. “I tend to snorkel during the spawning so I can have more time in the water. If you miss the spawning, you still get to dive the Barrier Reef…  it’s not so terrible.”

Liveaboard boats operating out of Cairns, like Tusa Dive, Mike Ball and Pro Dive, visit a number of Outer Great Barrier Reef sites, about 60km offshore. Dive depth varies anywhere from five to 35 metres, making these trips suitable for divers of all experience and certification levels. Travel time to and from the Outer Great Barrier Reef varies from 60 minutes to two hours. Trips can be booked anywhere from one night to seven nights. You can also head out to the Ribbon Reefs north of Cairns on three to seven-night expeditions. 

There aren’t any specific coral spawning liveaboard trips (even though it looks like there are on a Google search) departing from Cairns. It’s just a matter of coordinating your booking around the predicted coral spawning dates (no companies guarantee you’ll see the event).

You can also take a three day/ three night live-aboard boat out of Townsville with Adrenalin Snorkel and Dive, and you’ll have two night dives to see the spawning, as well as having the chance to visit rarely visited reefs like Wheeler’s Reef, and Australia’s best wreck dive, The SS Yongola.

While the Whitsundays region isn’t renowned for its coral spawning viewing opportunities, there’s always the chance it could be THE place to see it this season. Take a three day/ two night diving tour aboard the yacht, Kiana to try your luck.

You can even see it on land!

Rather not go on a boat at all? You can see the spawning from an island resort on the Great Barrier Reef. One of your best opportunities is on Lady Elliot Island. Though they don’t run specific coral spawning night dives, if you’re on the island during the event it’s easy to see the spawning.

“We don’t even need a boat, if the tide’s high enough we can see it night snorkelling in the lagoon,” says Lady Elliot Resort dive instructor, Kym Fiora “You don’t even have to get wet, we run night-time glass-bottom boat tours during the spawning, and it also often coincides with the first hatchlings of green turtles.” There’s also night diving available just offshore from the resort.

Have you witnessed coral spawning? Share your experience below.