Completing just one marathon can seem like a daunting task for many, let alone three back-to-back offroad marathons in Far North Queensland.

Fitness wasn't going to be a problem for experienced road runner Fleur Bromley but keeping watch for snakes, wild pigs and dangerous plants while covering 126.6km of rugged terrain was out of the Beach Haven resident's comfort zone.

Bromley, 33, conquered the challenge of running 42.2km each day for three consecutive days across the Tableland and Cairns and came out a winner.

The inaugural Three Marathons in Three Days event organised by the Cairns Road Runners started on July 6 and had a total ascent over the three days of more than 3600 metres and a descent of about 3800m.

Only 30km of the event was on bitumen. The remaining 96km was on terrain ranging from rocky, rutted and tree rooted single tracks to dirt road.

"The course took us over some spectacular, but gruelling country," Bromley says.

"Luckily I love the hills and have a good endurance base so was able to pick up the pace when others were hurting."

Bromley won the second and third day marathons, to finish the event as the first woman overall in a time of 15 hours 40 minutes and 10 seconds.

Of the 32 race starters, 25 runners made it across the final finish line. Helping to keep Bromley on track was her friend Lindsay who entered Bromley in the race as a birthday gift.

"Lindsay did a great job running alongside me, helping me through the 25 river crossings, encouraging me down some very steep descents and picking out the numerous thistles from vines that had lodged themselves into my limbs," Bromley says.

Bromley has previously competed in ultramarathons, ironman events and road marathons as well as representing New Zealand at the ITU Long Distance Triathlon World Championships in 2006.

- © Fairfax NZ News