Loch Sunart (Scottish Gaelic Loch Shuaineart) is a sea loch on the west coast of Scotland. Loch Sunart is bounded to the north by the Sunart district of Ardnamurchan and to the south by the Morvern district.
At 31 kilometres (19 mi) it is the longest sea loch in the Highland local government area. The maximum depth of the loch is 124 metres east of Càrna near the entrance to Loch Teacuis. Other islands in the loch include Oronsay, seaward of Càrna, Risga, which lies between the two larger islands, and Eilean Mòr, which lies towards the landward end of the loch in line with Beinn Resipol.
A considerable part of the loch is leased for aquaculture, with fish farming, originally only of salmon but now somewhat diversified, being established in the 1980s.
A local legend holds that the absence of resident swans in Loch Sunart is the result of a doomed love affair between a Celtic chieftain and a local girl. When his mother, who opposed a marriage, turned her into a swan to thwart their love, the young man accidentally killed the swan while hunting. On learning of the swan's real identity he killed himself to join the swan at the bottom of the loch, which swans supposedly have shunned ever since.