In sandals, with a small woven bag strung over her shoulder, 53-year-old Rose Tony scrambled up and down the steep mountains of the famous Kokoda Track, sleeping on bare ground and wading through rivers on an epic journey to see the pope.

A grandmother and mother-of-eight, Ms Tony is one of 23 people from Papua New Guinea's highlands who made the gruelling four-day trek to welcome Pope Francis to the country.

Flying from Indonesia, the 87-year-old is due to arrive in PNG at 7pm on Friday night on the second leg of his mammoth Asia-Pacific tour — the longest overseas trip of his papacy.

In PNG, a deeply Christian country with a large Catholic population, the visit holds profound significance for many.

Ms Tony said she was determined to see the pope, even if it meant risking her life.

"My family told me I would die on the way," she said.

"They told me I was unable to climb huge mountains. 'You will become sick or get injured.'

Starting their journey in the Western Highlands, the group travelled by boat and bus before embarking on the formidable 96-kilometre hike from Kokoda to Ower's Corner.

The historic track, utilised by Australian soldiers in World War II, is renowned for being extremely tough, with steep inclines, extreme humidity and the risk of tropical diseases.

While most people take eight days to complete the hike, Ms Tony did it in four.

"My Catholic faith pushed me to come here," she told ABC from Port Moresby.

"I want to set that legacy so when I am gone, my children will tell my story in the years to come."

John Ten, who was part of the group, said they ran out of food on the last day of the hike.

"Our legs were tired, we were hungry, we felt really weak," he said.

In a country with limited connectivity, many Papua New Guineans have gone to enormous lengths to reach the capital, where Pope Francis will spend most of his time before departing for Timor-Leste on Monday.

Nicky Domas, who is partially paralysed in one leg, walked hundreds of kilometres and travelled across six provinces to get to Port Moresby for the visit.

Mr Domas said he fainted at one point on the journey.

The 60-year-old hoped seeing the pope would bring a sense of peace and healing.

"If a king, queen or prime minister visits Port Moresby, I wouldn't have come here," he told ABC.

The Catholic church has a presence in PNG dating back to 1847 when the first missionaries arrived at Woodlark Island.

Nowadays, the Vatican estimates about 2.5 million Catholics live in the country — making it the largest Christian denomination in PNG.

Along with religious leaders from Australia and the Pacific, a number of government heads have also arrived in Port Moresby to welcome the Pontiff.

They include the prime ministers of Tonga, Vanuatu and the Solomon Islands, and the president of Nauru.

PNG Prime Minister James Marape said the pope's visit was deeply significant.

"Papua New Guinea is ready to welcome His Holiness, Pope Francis, to our country. I want to appreciate him and the Vatican for choosing to visit us amidst his very busy schedule," he said.

After landing at Jacksons Airport on Friday night, the pontiff will begin a packed schedule that includes meetings with government and religious leaders, school visits and a trip to Vanimo, a remote province at the border between PNG and Indonesia.

Upwards of 30,000 people are expected to congregate at Sir John Guise Stadium on Sunday morning when the pope holds a public mass.

Senior priest Father Giorgio Licini, who heads the Papal Visit Committee in PNG, said the trip was very much in line with Pope Francis's focus on reaching out to people at the peripheries.

He said there was also a personal aspect to his side-trip to Vanimo, where the pope has quietly supported a group of Argentinian missionaries based there.

"Those who organised the trip didn't include Vanimo in the first draft," Fr Licini said.

"But he [the pope] personally told them 'since I am going to PNG, I also want to go to Vanimo.'