The professional triathlete is on a roll this season after wrapping up 2015 with a stunning victory at the Ballarat Ironman 70.3 in December.

He then claimed fifth in his first race back from a two month break, finishing the 1.9 kilometre swim, 90 km bike ride and 21.1 km run in Busselton in three hours, 46 minutes and 53 seconds in a world class field.

Pellow's success has earned him his spot in the Ironman 70.3 World Championship on the Sunshine Coast on September 4, an event that will pit him against more than 3000 triathletes from around the world.

But before that he's gearing up for his debut race at the Ironman full-distance - a 3.9 km swim, 180.3 km ride and 42.2 km run - and while he doesn't know quite what to expect, Pellow said he's fitter than he's ever been.

"I've been doing some really long training sessions over this last month, doing some rides that are over four hours long and I've also been doing some run sessions that are over two hours long, and I'd call that high intensity," Pellow said.

"I actually think I'm fitter than I've ever been. I'm quite excited to get in to do this race."

Pellow has been in Cairns since Friday to acclimatise to the warmer weather, and said he has been able to get a feel for the course as well.

"You run along the esplanade, it's a lap course, you do three laps so you get a bit of a chance to have a look even during the race," he said.

"I've had a look at half the bike course... it is quite undulating. We ride from Cairns up to Port Douglas which is 65 m above.

"The wind normally blows from the east and there's certain sections of the course where it pulls you down and you have to stick it out and know that you'll feel and bit better around the corner."

Conditions in the open water swim will also be challenging, Pellow said, with jellyfish to contend with and murky water meaning competitors will need to sight above the water to check their progress.

It's going to be a big jump up for Pellow, who said his biggest challenge will be pacing himself over the longer distance.

"I haven't done it before so you can't really come up with a strategy until you know how your body's going to react," he said.

"The ride's going to be four hours long, the run's going to be two-and-a-half to three hours. That's why I picked this race, because there's going to be a lot of guys I'm going to be able to copy and then I'm hopefully I'm fit enough at the end.

"You've got to start somewhere. I've definitely done enough training...[but] you still can't replicate the race in training so you've just got to do one and trust that you've learnt enough over the years to get it right."