mountain island[10]) is a rural locality (a selo) in Bilibinsky District of Chukotka Autonomous Okrug, Russia, located southeast of Bilibino, on the banks of the Maly Anyuy River.

[13] In 1945, a weather station was built on the shores of the Lower Ilirney lake, and not long after that a state farm specialising in reindeer herding was established, around which a settlement grew up.

Additionally, the farm's name was changed to 40 Years of October (Russian: 40 лет Октября), and it became substantially more profitable as requirements from the expanding mining workforce increased demand significantly.

[13] A bonfire is lit, sacrifices are made and a variety of sporting competitions involving jumping, throwing and wrestling take place.

There is a small series of roads within the settlement including:[19] With a subarctic climate (Köppen Dfc), Ilirney endures bitterly cold weather for much of the year, with temperatures almost never rising above freezing between October and April, and sometimes plummeting below −50 °C or −58 °F in January and February, although the freakish month of January 1950 averaged 19.6 °C (35.3 °F) above the long-term normal[20] owing to a huge block in the Bering Sea that more famously produced a huge cold wave in western Canada and Washington state.