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
East Mouse East Mouse East Mouse () is an islet found off the north coast of Anglesey, Wales. It is found just a few hundred metres away from the town of Amlwch. For this reason the island is known in Welsh as "Ynys Amlwch", Amlwch Island. The islet is tiny (a maximum 141 metres long by 61 metres wide) with a maximum area of only , and void of any significant flora and fauna. The islet is one of three similarly named islands off the north coast of Anglesey, the other two being West Mouse (Maen y Bugail) and Middle Mouse (Ynys