THE Whitsundays biggest running event is approaching fast and organisers are encouraging everyone to get involved.

As an incentive to enter and get training, entrants will receive $10 off their registration fee and a free t-shirt if they enter before May 31.

The fourth annual Cruise Whitsundays Airlie Beach Running Festival will be held on Saturday, July 16 and Sunday, July 17.

This year, more than 1,000 runners, their family and friends, are expected to attend.

Event manager Wendy Downes said more than 600 runners participated in the festival last year.

"We're hoping to increase that again this year," she said.

"We have grown every year since we started and the event is attracting interest from all over Australia and overseas."

Local residents will compete with interstate and international runners for trophies in six different categories including a half-marathon, 10km and 5km runs and a 2km fun run for children competing in the Primary Schools Challenge.

There will also be a 5km Business Team Challenge and a three person half-marathon relay event.

Early bird entrants will also go in the draw to win a prize for two people worth $700 including a scenic plane trip over Heart Reef, thanks to GSL Aviation and a ride out to Whitehaven Beach and Hill Inlet with Ocean Rafting including snorkelling on the way.

Accommodation discounts are available for registered festival entrants from a range of accommodation partners.

For more information visit http://www.runairlie.com.au.