The Treshnish Isles are formed from 8 principal islands varying in size, with Lunga, the largest island in the archipelago.
The archipelago lies, at its closest, 3km west of Mull and extends along a northeast-southwest for a distance of 11km.
Apart from the scenery of the isles, their mystique as a group of uninhabited islands, holds nationally important treasures in the form of a mediaeval castle as well as a thriving community of wildlife.
Inhabited by huge colonies of seabirds, the islands have attracted travellers and visitors for at least 1000 years and some place names are rooted in the Viking language, reflecting their Hebridean rule.
The names of some of the islands still reflect their importance to the Vikings who once ruled in the Hebrides. The islands, and especially Cairnburgh Castle on the islands of Cairn na Burgh Mòr and Cairn na Burgh Beg, gave the Vikings and subsequent inhabitants such as the MacDougall, MacDonald and Maclean clans a strong strategic position until it was abandoned in the late 1700s.