Bursting with colour, edged with mountainous cliffs and nestled between Japan and the Korean Peninsula sits a sacred, World Heritage-listed "forbidden" island.
Okinoshima island is shrouded in taboos, rich in ancient treasures and boasts thousands of years of history.
It's also completely off-limits to women.
Deeply rooted in Shinto religious tradition, the 97-hectare island approximately 60 kilometres from Munakata city in Kyushu's Fukuoka Prefecture is one of very few locations in Japan that has been largely untouched since the ninth century.
Until 2017, only 200 men were permitted to visit the island for a single day each year for its annual On-Site Grand Festival.
The men had to observe strict religious prohibitions, said Miki Okadera of the secretariat of the Council for the Preservation and Utilisation of the Sacred Island of Okinoshima and Associated Sites in the Munakata Region.
She said they had to follow purification rituals performed naked in the waters surrounding the island upon landing, abide by the "Oiwazu-sama" taboo that forbids disclosing anything seen or heard on the island, and could not remove a single tree, blade of grass, or stone from the island.
Professor Simon Kaner is a member of the international expert panel that assessed Okinoshima's bid for World Heritage listing in 2017, and is one of only a handful of foreigners invited to visit the island.
"The island is surrounded by taboos," said Professor Kaner, who is the head of archaeology and heritage at the Sainsbury Institute for the Study of Japanese Arts and Cultures.
"I'm not supposed to tell anybody about what I saw and I wasn't allowed to take anything from the island."
[map of okinoshima]Out of respect, many even refrain from uttering the name Okinoshima, instead referring to the "island whose name cannot be spoken", the island's committee website states.
The island is home to a collection of some 80,000 votive offerings — national treasures, or artefacts — which were deposited there by envoys going back and forth between Japan and the East Asian mainland between the 4th and 9th centuries.
Sacred rituals using these offerings were conducted on the island to pray for the protection of the ships and the safety of the sailors.
"Okinoshima is a microcosm of many of the mysteries which surround Japan's ancient past and a treasure house which casts light on Japan's interactions with the ancient world," Professor Kaner said.
Since 2017 the island has been occupied by a rotation of two dozen Shinto priests from the Munakata Taisha Shinto shrine.
Public access without permission is a criminal offence.
Only one priest occupies the island at any given time, working a ten-day roster rotation undertaking rituals and general maintenance.
"The island remains an object of religious devotion to this day," Ms Okadera said.
Professor Kaner said one of those rituals was intended to venerate the spirits which they believe inhabit the island — the three female deities [or goddesses] of the Munakata Taisha shrines.
They believe the spirits have control over the straits between Kyushu and the Korean Peninsula, he said.
"Whether you believe in those abilities or not, I can say it's a place that has a very special atmosphere," he said.
It is the gender of these spirits, along with other beliefs about menstruation and impure blood, which are responsible for the island's exclusivity.
Japan's gender taboo rooted in religion
Okinoshima's exclusion of women comes from both the Shinto and Buddhist religious traditions according to Kaori Okano, a professor of Asian studies and Japanese at La Trobe University.
One of the Shinto beliefs is that the menstrual blood of a women is "impure".
"Menstruation and childbirth produce a lot of blood, and the blood itself is considered as somehow unclean and impure," she said.
But it wasn't until Buddhism came to Japan in the mid-sixth century that women were banned from Okinoshima completely.
"Buddhism brought in this more permanent view of women's inferiority and it made this idea [of impure blood] stronger," Professor Okano said.
Another important Shinto belief was that divine spirits — usually those of a goddess — reside in natural elements like mountains and seas, and can become "jealous" of other women and "upset" in their presence.
"Nature worship believes there is a god in the mountain, a god in the sea … so there is a god in Okinoshima island," Professor Okano said.
"And if there are female gods there human beings didn't want to upset the female god by involving women there."
Okinoshima is not the only sacred place in Japan to ban women.
Gender exclusivity is woven throughout traditional Japanese history with women banned from many mountains, temples, places of worship and Shinto sacred sites for thousands of years.
These exclusions continue to have ramifications in contemporary society.
Could Japan's first PM challenge gender beliefs?
Japan this year ranked 118th out of 148 countries in the Global Gender Gap Index (GGGI), the lowest among G7 nations.
Professor Okano said that while Japan scored highly for women's education and health, it ranked poorly in politics, employment and the economy.
"In comparison to other First World countries, the women's status is low, and there's definitely a gender division in terms of family responsibility and employment," Professor Okano said.
In October the country elected its first female prime minister, Sanae Takaichi.
However, not long after she took the top job she was forced to let a male advisor step into the ring to present the Prime Minister's Cup to the winner of an annual sumo tournament due to the sport's longstanding ties to Shinto tradition.
Professor Okano said she did not believe Ms Takaichi would spend her reign directly challenging gender divisions in the country.
"She's a right-wing thinker in terms of defence and economy and she's against the idea of allowing married women to maintain their maiden names. So I don't think she is progressive," she said.
"However, the fact that she, a woman, became prime minister — you can't become something that you have never seen."
Nostalgia of tradition and gender discrimination
Professor Okano questioned whether the World Heritage Committee should have granted Okinoshima its listing while women were still banned.
"Having Okinoshima as World Heritage in a way legitimatises this gender-specific practice," she said.
She said bans on women visiting many mountains in Japan for the same religious beliefs had been scrapped and people had still been able to continue practising their religion.
"Even though from a feminist perspective this is a gender discrimination — kind of systemic exclusion of a woman from visiting some places or participating in certain activities — some people may see this as a nostalgic tradition," she said.
"And sometimes people — not everyone — tend to romanticise tradition.
"But in order to emphasise nostalgia for the tradition you don't have to practice it today."
She said the topic was heavily debated when Munakata city was nominating Okinoshima for World Heritage.
Professor Kaner said the prohibition on women visiting the island had been "one of the really problematic aspects of the World Heritage inscription".
"I would never say that the example of Okinoshima should be used in order to encourage more places to exclude anybody of any gender or any religious bent or anything at all," he said.
Preserving Okinoshima's sanctity
A UNESCO spokesperson told the ABC that the island and its surrounding sites were granted World Heritage status on the basis of its Outstanding Universal Value (OUV).
According to the World Heritage listing these include the cultural tradition of worshipping a sacred island and important exchanges amongst the different polities in East Asia between the 4th and the 9th centuries.
"In the island's nomination dossier the longstanding customs and ritual practices associated with the property were described," the spokesperson said.
"However, the gender concerns were not raised with regard to its OUV, integrity, authenticity, protection and management.
"UNESCO does not intervene in the social, cultural, or religious practices that fall within the domestic affairs of its state's parties.
"Regulations concerning access to sacred sites are addressed within national legal and cultural frameworks and fall under the responsibility of the state party concerned."
The UNESCO spokesperson said there are other World Heritage sites where certain individuals may be prohibited from entering into certain areas and/or participate in rituals including Mount Athos in Greece, Sacred Mijikenda Kaya Forests in Kenya, Lake Baikal in Russia, and Uluru-Kata Tjuta National Park in Australia.
"It is noteworthy that UNESCO continues to promote gender equality as a global priority, while respecting the framework of the World Heritage Convention and cultural diversity," the spokesperson said.
Professor Kaner said the gender exclusion was "an issue that's recognised by the shrine authorities, and that's why they decided to no longer allow the larger groups of men [who visited annually] to go there anymore".
"Many of [these objects that] have now been designated as national treasures have tremendous value for both Japan and for people all around the world in understanding the contribution that Japan has made to world history," he said.
"In the same way that a place like Uluru now has restricted access, these kinds of restrictions — ideally not gender based ones — are one way to not control, but maintain the original state of some of these sites which are perhaps more fragile in nature than others."
