It was as if the last person in each heat was actually the first.

The swimmers who had finished were clapping their fellow competitors, egging them on to the end.

Unlike most major international sporting events, the Invictus Games are about so much more than just winning.

"I tell you what: you can't predict that feeling, it's goose-bump feeling, it sends tingles down your spine," Vanessa Broughill told AAP on Tuesday.

Broughill and Australian teammate Nathan Whittington both won their 50 metre freestyle heats to reach Wednesday's finals.

"Words can't describe the sound of the crowd," Whittington told AAP.

After joining the army at 18, Whittington lost his foot in a jet ski accident less than a year later.

His dreams of rising through the ranks tragically quashed, he turned his attention to sport to aid his mental and physical recovery.

After achieving his goal of walking the Kokoda trail with a prosthesis in 2015, he set his sights on the 2016 Paralympics. Failing that due to injury, the 2018 Invictus Games gave him reason to train and improve his fitness once again.

"Yeah, to get a spot in the finals in front of my friends and family, to look up and see a smile on my old man's face and to get a thumbs up, it's really good," Whittington said.

Broughill finished her heat with a personal best but the goose bumps she was feeling had little to do with beating the other competitors.

"These Invictus Games literally changed my life, they dragged me out of the house, gave me a purpose to become a better version of myself," she said.

After four years in the army Ms Broughill moved into an electronic intelligence role with the navy. But the stress of her role and multiple shoulder operations left her feeling depressed and anxious.

"The medication, physiotherapy and psychology I had been doing kept me from really dark pathways but it was the Invictus Games that gave me my life back."

With no medal tally at the Invictus Games, the challenge is all about the physical and mental obstacles the competitors have overcome.

Making up a significant number in the crowd are the family and friends supporting their loved ones, having witnessed first hand the transformative effect their training and participation has had.

"People often say to us Invictus is just like the Olympics or the Paralympics but I tell you what, it's nothing like it, you do not get the camaraderie in any other sporting event that you do here," Broughill said.

As well as preparing for their finals tomorrow Broughill will be competing in shot put and discus while Whittington will be racing in multiple athletics events.

Australian Associated Press