Ynys Enlli has become the first site in Europe to be awarded International Dark Sky Sanctuary status.
Also known as Bardsey Island, located two miles off the tip of the Llŷn Peninsula in the north Wales coast, Enlli was granted the certification by the International Dark Skies Association on Thursday.
Becoming one of just 17 sites across the world, these areas are typically situated in very remote locations with few nearby threats to the quality of its dark night skies.
The location and geographical features make Enlli one of the darkest places in the UK with a mountain on the island naturally limiting light from the mainland. The nearest major light pollution comes from Dublin, more than 70 mils across the Irish Sea.
A four-year programme was completed to monitor the quality of the night sky on the island, along with a lighting management plan and photographic evidence required for the certification.
Sian Stacey, Chair of the Bardsey Island Trust, said she was "delighted" at the news: "It is a huge achievement and I would like to thank all who have been involved. It’s the culmination of several years hard work involving our own team as well as our partners across the region and beyond.
"There’s no doubt that achieving this prestigious status for Ynys Enlli will raise the profile of the island as a unique place in Wales and amongst the best in the world to appreciate the night sky. We hope it will also go a long way in securing the long-term sustainability of the island."
A sanctuary differs from a Dark Sky Park or Reserve in that it is typically more remote. Wales already has an official Eryri National Park covering more than 820 square miles, in addition to the Brecon Beacons National Park which stretches 1,344 square kilometres.
Making up the other 16 sanctuaries across the globe, there are sites in the US, Chile, South Africa, New Zealand, Australia, Niue and the Pitcairn Islands.
The population of Ynys Enlli has fluctuated over the centuries and is now home to a small community of residents who work the land and fish from the island.
As well as a Bird and Field Observatory, there are ten cottages in the region for visitors to escape modern life during the holiday season.
Executive director of the International Dark-Sky Association, Ruskin Hartley, said he was "pleased to welcome Ynys Enlli to the growing community of dark sky places worldwide".
He added: "With it, Wales is fast becoming one of the leading nations in protecting dark skies as a precious resource that benefits people and wildlife."
Mari Huws lives on Ynys Enlli and is one of the Wardens who has been part of the certification process: "Living here I am always in awe of the island’s beauty – and the night sky is very much a part of that. Having secured the certification, we look forward to welcoming visitors here over the coming months and years and sharing with them our unique story.
"We knew we lived in a special place, this new status confirms this, with IDSS putting Enlli firmly on the global stage. In a world that's increasingly being polluted, it's a privilege to be able to work towards protecting something that is pristine for future generations."