A South Australian veteran who died during a fundraising walk along the Kokoda Track in Papua New Guinea is being remembered as a "loving" father of five.
Paul Miller had been walking the path with his son when he suffered what is believed to have been a heart attack.
The trek was intended as a fundraising effort run by veterans and first responders support group Operation Unity SA.
Mr Miller's partner of 23 years, Amanda Kaplan, said he was a "loving" partner and father of Sarah, Sabrina, Hayley, Aaron and Amy, who passed away aged 12.
"Paul was a proud and extremely well-respected member of the veteran community," she said.
Ms Kaplan thanked those in Papua New Guinea who had done what they could to try and save Mr Miller.
"Personal thanks to Raymond who escorted our son Aaron home during this tragic time, he remained with Paul and made all efforts to save Paul's life," she said.
Mr Miller joined the army at the age of 16 as a vehicle mechanic apprentice in 1991, Ms Kaplan said.
During his more than two decades of service, Mr Miller worked across Australia, was deployed to INTERFET in East Timor, served in Iraq and Afghanistan before being discharged in 2014.
Mr Miller retired due to mental health-related issues and has since used his time to advocate for other veterans.
"Paul was an avid sports fan and members of Sydney Roosters, Western Force, and Queensland supporter for State of Origin, Freo Dockers," Ms Kaplan said.
'Mate to many and a brother to me'
Operation Unity SA confirmed Mr Miller's death in a Facebook post, prompting a wave of condolences from friends and members of the public.
"Rest in peace, digger," one wrote.
"He was an amazing asset to the both the veteran and greater community and will be solely missed by everyone," another person posted.
MP Tony Zappia also expressed his "deepest sympathy" to Mr Miller's family.
"A dedicated supporter of veterans, first responders and their families," he wrote.
A colleague of Mr Miller shared a message on Facebook from the Adelaide Veterans Coffee Group, who said it was with a "heavy heart" that they were notifying their members of the tragedy.
"Paul 'Dusty' Miller passed away during his charity walk in PNG. He was a mate to many and a brother to me," the statement said.
"Lest we forget."
It is understood CPR was performed on Mr Miller and that he was airlifted to hospital, where he was confirmed to have died.
Local police investigating, Kokoda authority says
Kokoda Track Authority Acting CEO Julius Wargirai said he felt for Mr Miller's family.
"I hope to talk to Adventure Kokoda and sort this out, we all need to cooperate with the police to provide information," he said.
"Police have started their investigation, they're heading for the track now.
"They're trying to collect information from villagers and those involved from Adventure Kokoda."
He said a post-mortem will be carried out.
The ABC has contacted Adventure Kokoda for comment.
In a statement to the ABC, the Department of Foreign Affairs and Trade said it was providing consular assistance.
A spokesperson for DFAT extended "our deepest condolences to the family".
In earlier posts, Operation Unity SA described Mr Miller and his son as "intrepid adventurers" who were undertaking an "extraordinary effort".
"An adventure of a lifetime and done as father and son," the group stated.
Mr Miller had been training for the Kokoda Track walk by hiking up Adelaide's Anstey Hill.
Money raised from his walk had been destined for charities Operation K9 — which trains assistance and service dogs — and Soldier On.
