St Kilda - Coastal The dramatic stacks and cliffs of the St Kilda group are the remnants of a volcano which erupted 60m years ago. Boreray is the biggest stack, and Soay the largest island. All of the coastline is rugged and formed from volcanic rock. Sac an Armin and Stac lee accompany Boreray, while Levenish lies to the east. Stac an Arin Boreray & Stacks Boreray & Stacks Boreray & Stacks Stacks from "Bowen" "Bowen" in Glen Bay Gob an Duin Dun from SW Glen Bay Arch Levenish & Hirta Glen Bay Arch Oiseval Cliffs Soay & Mullach Bi Sound of Soay Sound of Soay Hirta from "Bowen"