Malcolm Turnbull has swapped his signature Hermes ties for a hibiscus shirt during a day-long trip to Samoa to talk trade and aid with Pacific leaders.

The prime minister touched down in Apia on Friday morning and was quickly whisked away to a beachside resort for the annual Pacific Islands Forum.

Mr Turnbull bypassed the buffet breakfast and infinity swimming pool as he sat down for a one-on-one meeting with Charlot Salwai, the Prime Minister of Vanuatu.

He was quick to congratulate his counterpart for signing onto the PACER Plus trade deal.

Vanuatu had been holding out, but signed onto the regional trade deal on Thursday, with a request for more development assistance from Australia and New Zealand.

The leaders discussed the free movement of seasonal workers, as well as combating crimes including money laundering and terror financing.

Afterwards, a relaxed-looking Mr Turnbull snapped a selfie with NSW holidaymaker Gail Fairweather as he strolled through the resort.

The 19 Pacific leaders, dressed in matching tropical shirts, gathered for an awkward classroom-style group shot in front of a heaving international press pack.

The costume-coordinated cohort was then herded into a unique “lock in” known as the forum leaders retreat.

The event sees all leaders held as willing captives for roughly six hours to hammer out goals and grievances.

Heads of tiny, sparsely populated island nations take their seats alongside much larger and more powerful neighbours including Australia and New Zealand.

Personal aides and policy boffins are left outside as politicians strive to reach consensus on various regional issues in private.

The North Korean crisis will loom large over the meeting, as leaders discuss global conflict, power and international relations.

Tackling climate change and rising sea levels will also be critical as politicians discuss food security, sustainable development and the depletion of natural resources.

So too will talks on maximising incomes from fisheries, tourism, deep-sea mining and labour mobility and governing how the earnings are spent.

Mr Turnbull is due to sign a raft of agreements with four Pacific neighbours – Nauru, Tuvalu, Kiribati and Tonga – later on Friday.

The deals are expected to centre on workers’ rights in Australia and pharmaceutical trials.

He will also sit down with the prime minister’s of Papua New Guinea and Samoa, as well as the forum’s secretary general.

– AAP