West Loch Tarbert (Scottish Gaelic: Loch A Siar) is a sea loch that separates the northern and southern parts of the island of Harris in the Outer Hebrides of Scotland. A small isthmus joins these two areas, on which is to be found the village of Tarbert. The loch contains the islands Soay Mòr, Soay Beag and Isay, while Taransay lies near the mouth of the loch.