Mousa is a small island in Shetland, Scotland. The island is uninhabited and is best known for the Broch of Mousa, an Iron Age round tower. It is designated as a Special Protection Area for storm-petrel breeding colonies. The island also houses grey and common seals, guillemots, Arctic terns and storm-petrels. In summer a small tourist ferry visits the island once a day and remains there for a few hours, providing plenty of time to walk around the island and visit the broch.