The head of the loch lies near the village of Tarbert and it reaches the open sea at Ardpatrick Point some 15 kilometres (9.3 mi) distant.

He made an arrangement with King Malcolm III of Scotland that he could take possession of land on the west coast around which a ship could sail.

Magnus declared that Kintyre had "better land than the best of the Hebrides", and by taking command of his ship's tiller and "sailing" across the isthmus he was able to claim the entire peninsula, which remained under Norse rule for more than a dozen years as a result.

This served Port Askaig on Islay, in competition with the mail steamer, operated by MacBraynes from West Tarbert near the head of the loch.

In this guise, she took on a new timetable – three double crossings a day between modified terminals at Port Ellen and West Loch Tarbert.