Not far away, in suburban Canberra, two young sisters whose father died by suicide in 2008, will pause and celebrate the Gays' achievements.

Two families. Two tragedies. One determination to make a difference.

Will, 23, and Maddie, 27, started their journey to climb six mountains – Mount Kinabalu in Malaysia, Machu Picchu in Peru, Mount Meru in Tanzania, Mount Kilimanjaro in Tanzania, Mount Cook in New Zealand and Mount Kosciuszko in Australia – in September, in memory of their father, Tony, and to raise money for Lifeline.

They called their campaign 6NIL – six mountains, five countries, four continents, three months, two people, one goal: zero suicides.

The siblings, who have raised $130,000 for Lifeline's 24/7 crisis support and suicide prevention services, plan to finish their epic journey about noon on Saturday at the summit of Mount Kosciuszko, surrounded by about 100 family and friends.

Maddie said she expected the finish to be "very emotional and a bit strange" as they had devoted so much time to achieving their goal. Their father, a farmer from Boorowa with a history of depression, would be close to their hearts as they reached the finish line.

"Every day we think about him and also wish the outcome was different, but we also know we can carry him with us and the lessons he taught us," she said.

"You just think you have to keep going and lead the really good life Dad wanted for us. He always wanted the best for us and he told us we could do anything."

Maddie and Will, who quit their jobs to go on their journey, said the attempted suicide of a cousin, in 2013, was the final push towards planning their trip.

"I'd had enough of wonderful people taking their life or attempting to and I thought, 'This is enough. We've got to do something'," she said.

Each mountain had been a fantastic experience, although the massive Mount Kilimanjaro had been emotionally and physically draining. It was all worth it to try to prevent suicide, with Lifeline Australia chairman John Brogden recently calling for suicide to be declared a national emergency. Seven Australians take their own life every day.

The efforts of the Gay children have not gone unnoticed in Canberra.

A fundraising dinner for 6NIL will be held in the national capital on November 21, organised by University of Canberra dietician and lecturer Nerida Volker, whose then husband Peter Smith died by suicide in Cowra in 2008.

Their daughters were only four and eight at the time.

Ms Volker, who has since re-married, said helping children to cope with the loss of a parent was hard enough, but a death by suicide could be very difficult.

"For families bereaved by suicide the grief is complicated by the associated stigma," she said.

"For children, it can be difficult to understand the reaction of the adults around them. Their lived experience of suicide is not often heard and that is why Will and Maddie's efforts are so important."

Ms Volker said she had been moved by the efforts of Maddie and Will and believed they provided a fantastic example to her own children.

"Maddie and Will are such wonderful role models for my girls in terms of being very courageous about telling their story and also wanting to do something about raising awareness about suicide prevention.

A special guest at the dinner in Canberra will be Paralympian gold medallist Kurt Fearnley, who was a cousin of Peter Smith and who finished the gruelling Kokoda Trail in memory of Peter in 2009.

Mr Brogden said the Canberra dinner showed the powerful and far-reaching influence of Will and Maddie's journey.

"It has been touching to follow the progress of Will and Maddie's challenge, 6NIL," Mr Brogden said. "The two said they wanted to do something 'huge' for suicide prevention following the death of their father Tony in 2009, and they have certainly achieved this."

The dinner will be held at the Erindale Vikings on November 21. Ms Volker is calling upon the Canberra community to get behind the event, donate to Lifeline and help the national charity take steps towards its vision of an Australia free of suicide.

Tickets to "An evening with Kurt Fearnley and 6NIL" can be purchased from the Eventbrite website. The event is supported by the Erindale Vikings, with all profits going to 6NIL's campaign for Lifeline.

For crisis or suicide prevention support, please call Lifeline on 13 11 14 or visit lifeline.org.au/gethelp.