Loch Tarbert is a sealoch and sheltered anchorage located on the west coast of the island of Jura, Argyll and Bute. However, it almost splits the island in two, with the head of the loch lying just ¾ mile (1.2 km) to the northwest of the settlement of Tarbert, which is situated on the island's east coast. It extends for 7½ miles (12 km) and is divided into three sections; the outer loch is divided from the middle section by a narrow channel named Cumhann Mor, while the inner loch is another 2 miles (3 km) east and separated by Cumhann Beag, which is barely 35m (155 feet) in width. The inner loch is shallow surrounded by an extensive sandy beach.
Loch Tarbert is of international geomorphological importance as the location of several post-glacial raised beaches and some of the finest examples of unaltered raised shore platforms and unvegetated raised shingle ridges in Western Europe.
