Leaders from across the region are descending on Tonga this week for the annual talks.
Difficult issues - including unrest in New Caledonia, climate change, and growing geopolitical rivalries in the blue continent - are likely to weigh on leaders across the PIFLM program, which climaxes on Thursday at the leaders' retreat.
However, as is customary in Tonga, little diplomatic business was done on Sunday.
The Centenary Church, the seat of the Free Wesleyan Church of Tonga, in Nuku'alofa, Tonga. (Ben McKay/AAP PHOTOS)
Instead, leaders arrived at the Centenary Church, the seat of the Free Wesleyan Church of Tonga, for a special service in honour of the visitors.
Sunday is respected as a day of rest across deeply-religious Tonga.
It's not just custom but law: enshrined in the constitution to be "kept holy".
Few exceptions are made.
Markets and local shops open late on Saturday to allow for last-minute shopping and preparations for gatherings the next day, and don't open again until Monday.
So instead, leaders arrived at the stately white church on Sunday morning, joining hundreds of locals.
Tonga's Princess Angelika Tuku'aho represented the royal family, with King Tupou VI reportedly staying away from the main island of Tongatapu during the summit.
United Nations Secretary General Antonio Guterres attended, as did Fiji Prime Minister Sitiveni Rabuka, Samoan Prime Minister Fiame Naomi Mata'afa and others.
Young Tongan churchgoers enjoyed Sunday service - with a few extra guests in town. (Ben McKay/AAP PHOTOS)
Australia and New Zealand's prime ministers are expected to join the summit mid-week.
They missed a mighty cook-up, with hundreds of churchgoing delegates then transferring to the Queen Salote Memorial Hall to lunch on suckling pig, crayfish, octopus and fish, all while a local choir sang on.
The extravagant feast precedes a challenging week.
There are no shortage of issues facing the region, and no lack of participants eager to engage.
More than 1000 delegates have been accredited, including government officials, media, and NGOs.
Geopolitical giants China and the US are bringing large and powerful delegations to the summit, with Qian Bo, the Special Envoy for Pacific Island Countries Affairs, representing Beijing.
Kurt Campbell, President Joe Biden's Deputy Secretary of State, and a key architect of AUKUS, will front the American grouping.
Pacific island nations are among the world's poorest, in need of development assistance and support from larger nations on a multitude of issues.
The US and China have been told by Pacific Islands Forum secretary general Baron Waqa not to disturb the Pacific peace.
"We don't want them to fight in our backyard here. Take that elsewhere. You know we are peaceful people (and) region," he said last month.
Pacific leaders and the UN Secretary General enjoyed a church service in Tonga on Sunday. (Ben McKay/AAP PHOTOS)
China's shadow in particular is evident in Tonga, with a number of construction projects funded by Beijing - including the main venue for this week's deliberations.
The United States has recognised as such, opening an embassy last year.
Another non-PIF power, France, is also deeply involved in this year's deliberations, as the colonial power of crisis-hit New Caledonia.
The French government has imported police to restore order in New Caledonia after riots earlier this year, but a political impasse remains between Paris and the pro-independence Kanaks.
Differing views across the region on a pathway to self-determination means this issue will not be solved in Tonga: though there are hopes a united Pacific position can be reached.
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