North Stack North Stack North Stack (Welsh: Ynys Arw, meaning "rugged island") is a small island situated just off Holy Island on the north-west coast of Anglesey. North Stack can also refer to the headland opposite the island. This is the site of a redundant fog warning station, comprising a number of buildings, including the Trinity House Magazine, built in 1861, where shells for the warning cannon were stored. These buildings now house a bird watching observatory, giving a view of South Stack lighthouse across Gogarth Bay, and the studio of artist Philippa Jacobs. The Precambrian quartzite cliffs of this headland, including
Anglesey near the north coast. There are plans for the world's first Tidal Flow turbines, near The Skerries, off the north coast, and for a major biomass plant on Holy Island (Ynys Gybi). Developing such low-carbon energy assets to their full potential forms part of the Anglesey Energy Island project. When the aluminium smelting operation closed in September 2009, it reduced its workforce from 450 to 80; this has been a major blow to the island's economy, especially to Holyhead. The Royal Air Force station RAF Valley (Y Fali) is home to the RAF Fast Jet Training School and also 22