The "dressed-down" monarch had a garland of dried fruit placed around his neck and was later honoured with a new title.

Despite the rain, he was in good spirits and clutched a bamboo-handled umbrella as he met locals.

The 75-year-old took part in a traditional ava ceremony, with the drink prepared by the daughter of Samoa's head of state.

As is custom, the King poured a few drops away before drinking deeply from a cup made of coconut shell.

He was wearing a short-sleeved white "Royal Navy"-style bush jacket and trousers he designed himself.

The jacket, similar to an elei, a short-sleeved shirt worn by Samoan men, was made by Anderson & Shepperd and featured fabric trim by the Samoan School of Arts.

The ceremony took place at the Pacific island's national university in a falesamoa, a large open-air covered hall made from timber.

A garland of dried fruit from the pandanus tree was put around the King's neck at the end of the ritual, while the Queen was given a floral arrangement.

They were also given a selection of gifts, including a pig carcass for feasting.

The ceremony was watched by village elders and dignitaries including Samoan Prime Minister Afioga Fiame Naomi Mata'afa and Foreign Secretary David Lammy.

Later, the chief of Moata'a village urged the monarch to "take a small part of Samoa away" as he made him Tui Taumeasina or King of Taumeasina.

"Once he has the title of Tui Taumeasina we also become part of him and he will be connected to our people and our lands forever," said Tofaeono Lupati Fuatai.

The chief also praised the King for his efforts highlighting climate change, of which Samoa is particularly vulnerable to through events such as cyclones, flooding and storm surges.

"The King is the perfect advocate for us as a nation," he said.

"Climate change is real, it is now and we must urge the world to acknowledge how perilous it is for nations such as ours."

The royals' stay in Samoa follows their brief tour of Australia earlier this week when a senator controversially heckled the King in parliament.

Read more:
King's trip Down Under wasn't without its challenges
Where is King head of state outside UK - and is he wanted?

On Friday, the King will be at the Commonwealth Heads of Government Meeting (CHOGM), which is being held in the Samoan capital, Apia.

Prime Minister Sir Keir Starmer has also touched down on the island nation of 218,000 after rejecting calls for reparations on slavery.

"I've talked to a lot of our Commonwealth colleagues in the Commonwealth family and they're facing real challenges on things like climate in the here and now," he told reporters on the plane.

"That's where I'm going to put my focus," he added. "Rather than what will end up being very long, endless discussions about reparations on the past."

However, the three hopefuls to become the Commonwealth's next secretary-general - from Ghana, Lesotho and Gambia - all back financial reparations.

This year's summit is also missing the leaders of the two biggest Commonwealth countries, India and South Africa.

Narendra Modi and Cyril Ramaphosa are instead at Vladimir Putin's meeting of the BRICS developing nations group.