Runners are being encouraged to sign up to the Great Barrier Reef Marathon before it’s too late. 

The event’s Early Bird discount opportunity expires on Friday August 15. 

Anyone that signs up but becomes unable to attend has a 30-day window to cancel their registration.

The Great Barrier Reef Marathon, which was recently listed as #3 on Australia’s Top 10 Regional Marathons by Australian Marathon Review, features race lengths ranging from 5 to 74 kilometres and will be held on November 9 at Four Mile Beach. 

In addition to the Early Bird Discount, groups of more than 10 runners are eligible for a 20 per cent discount. 

The marathon is positioned as a boost to the region’s traditionally quiet late-year tourism season, with runners often building an extended holiday in the area around their participation in the race.

$20 from each registration for the Great Barrier Reef Marathon will be donated to the Great Barrier Reef Research Fund, a collaborative conservation program between James Cook University and Eye-to-Eye Marine encounters. 

Port Douglas Events Management, which organises the Great Barrier Reef Marathon, has also partnered with North Queensland Bendigo Bank branches to host five-kilometre Run for the Reef events in Port Douglas, Smithfield, Atherton and Innisfail.

Runners can sign up on the Bendigo Bank Run For the Reef Challenge Facebook page from September 1. 

Port Douglas Events Management sales and marketing officer Jess Coleman said the Great Barrier Reef Marathon offered a 'totally unique' mix of terrains in picturesque surroundings. 

"There's no other marathon in Australia with beach, hills, rainforest and canefields all in the same run," Ms Coleman said. 

"When the some comes up on your left in the morning at the start, it's pretty magical.

"It'd be a real shame for anyone to miss out so they should get in and register quickly."

The Great Barrier Reef Marathon also has a Facebook page available here.