Okinoshima is a tiny island below South Korea, that belongs to the city of Munakata in Fukuoka, Japan.
The land mass is governed by a set of rules steeped in ancient tradition, including a ‘no women’ policy.
Okinoshima has just been declared a World Heritage site by the UN’s cultural body.
The Unesco honour included the island, three nearby reefs and four other related site.
Announced at the organisation’s annual summit in Krakow, Poland at the weekend, the World Heritage nod brings Japan’s total to 21.
The sacred island has long been the subject of intrigue thanks to its extremely unique features.
Okinoshima has a population of one: the lone employee to the shrine which resides over the sacred land.
It covers just 240 acres and rises 244m at its highest point.
But the most peculiar part of the island lies in its rules of entry, specifically who can and cannot step foot on its shores.
Women are completely banned from accessing the island due to an overarching religious tradition.
Okinoshima is considered a shinto kami, which adheres to an ancient Japanese religion focusing on diligent rituals.
The priests who work on the island enforce the female entry ban, but the exact reason why it exists remains shrouded in mystery.
According to the Japan Times, it might have something to do with women having periods.
Writer Ryo Hashimoto said: “There are varying explanations for the ban, but some say it is because menstruation would defile the site.
“Shinto treats blood as an impurity.”
Another theory is that traveling to the island by boat used to be extremely dangerous and so women were forbidden from going as a protection offering.
Even for men, access to Okinoshima is difficult. All visitors must strip naked and take part in a purification ritual before they arrive.
They are only allowed to visit one day per year, on May 27, to celebrate a festival dating back to 1905.
No one can take anything from the island upon leaving, not even one piece of grass.
Another condition for entering is to keep the details of your visit a secret when returning to the outside world.
Closer to home, the UK’s Lake District has also been awarded Unesco World Heritage status, after a 20 year battle for the privilege.
