Only men can put the mystical Okinoshima on their UNESCO World Heritage Sites must-see list. The sacred Japanese island, among several added in 2017 to the prestigious list of monuments with historical significance, is prohibited to women. Steeped in the traditions of the ancient Shinto belief system in Japan, Okinoshima has been revered by Japanese seafarers well more than a thousand years. Tens of thousands of artifacts from across the world, kept on the island as ritual offerings over centuries, are evidence of the rich cultural heritage of the region. Okinoshima is worshipped for its kami – or divine being – and access is ordinarily prohibited to all except Shinto priests. Strict taboos Women are prohibited from visiting because of ancient taboos, that also prohibit the eating of four-legged animals and prevent anyone from leaving the island without priestly permission. Only 200 men can visit the island once a year, on May 27 for a grand festival – and only after a process of misogi ablution that involves bathing naked for ritual purification. You cannot speak a word of what you see or hear in Okinoshima to the outside world and cannot carry anything – including a mere blade of grass – back with you. In fact, fishermen from the region refrain from taking even a pine branch floating in the water around the island. Why women cannot visit the island remains unclear. Speculation about the tradition’s origin ranges from a Shinto belief in the impurity of menstrual blood to a concern for the safety of women in dangerous waters. Priceless artifacts More than 80,000 artifacts have been unearthed in Okinoshima, including comma-shaped beads, shards of Persian glass, and gold rings. Declared collectively as national treasures of Japan, these are testimony to the rich overseas exchanges of the region. Since ancient Japanese rituals only began to be recorded after the 8th century CE, the island is a crucial source of information about the development of religion in Japan. Although a presence on the World Heritage Sites list usually leads to a flurry of tourist activity, there are no plans to open Okinoshima to the public. Visitors can pay homage to the shrine from a coastal terrace on the north side of the island as part of a tradition of worshipping the kami from afar.