The mythical sea-kingdom of St Kilda is an isolated archipelago situated 40 miles west-northwest of North Uist, in the North Atlantic Ocean. It contains the westernmost islands of the Outer Hebrides of Scotland. The largest island is Hirta, whose sea cliffs are the highest in the United Kingdom. St Kilda has Europe’s largest colony of seabirds including gannets, puffins and fulmars. The islands support unique species including the ancient soay sheep, a large wren and a sub-species of mouse which is twice the size of a British fieldmouse. It is an island environment unmatched anywhere in the world. The last inhabitants left in 1930.