Exploration of Teti'aroa has uncovered sites used by holidaying Tahitian chiefs for offerings, ceremonies and the Polynesian practice of fattening children.

The US film star fell for Teti'aora - as well as his on-screen love interest, the French Polynesian actress Tarita Teriipia - while filming Mutiny on the Bounty in 1962.

Their son, Teihotu Brando, still lives on the island which the family still part own.

The tiny island, a quick 45-kilometer canoe trip from Tahiti, has been identified as home to more than 100 structures associated with royal relaxation rituals.

The archaeological findings, from the Australian National University lead study, included archery platforms and an open-air altar.

While the chiefs practiced archery, their children were kept inside for weeks on end and fed a high-calorie diet of fermented breadfruit and coconut water, ANU archaeologist Dr Guillaume Molle said.

"In ancient Polynesian society it was seen as evidence of prestige when you were very fat because it meant that you had a lot of food at your disposal and you were not a poor person working in the valley.

"Also having the white skin meant you didn't have to spend the whole day working in the sun in the tropics," he said.

Dr Molle said no commoner would have had any use for archery platforms, as it was a sport for the elite.

"In Tahitian society [archery is] used for displays of strength, power and status and we have two here in Teti'aroa," he said.

Alongside researchers from Germany, New Caledonia and Teti'aora, Dr Molle spent more than 9 weeks on the tiny atoll which members of Brando's family still call home.

The research, which will continue when coronavirus travel restrictions ease, has been conducted with support of a scientific research center Brando established on the island.

Dr Molle said previously the theory of the island as a Tahitian royal getaway was based on literature and folklore.

The team set off to the island to find proof of the chief's activities.

Dr Molle said the number of sites of archaeological significance and their level of preservation had taken the them by surprise.

"These atolls are really susceptible to cyclones and tsunamis that tend to wash away the structures," he said.

"But Teti'aroa is pretty protected and what we've recorded is pretty amazing."

Researchers uncovered open-air temples, or Marae, which Polynesian cultures used in rituals to acknowledge their ancestors.

Dr Molle said carved volcanic stones were also found which they believe could have come from Tonga or New Zealand, a distance of more than 4000 kilometres away.

"All the other islands in this archipelago are high islands so the nature is very different in terms of landscape and ecology, you have resources there that you can't find on the high islands," he said.

"That probably attracted the Polynesian royals very early on."

The study is currently scheduled to resume in 2021.