The
River Tay (
Scottish Gaelic:
Tatha) is the longest
river in Scotland and the
seventh-longest in the United Kingdom. The Tay originates in western Scotland on the slopes of
Ben Lui (
Beinn Laoigh), then flows easterly across the
Highlands, through
Loch Dochart, Loch Iubhair and
Loch Tay, then continues east through Strathtay (see
Strath), in the centre of Scotland, then southeasterly through
Perth, where it becomes tidal, to its mouth at the
Firth of Tay, south of
Dundee. It is the largest river in the UK by measured
discharge. Its
catchment is approximately , the
Tweed's is and the
Spey's is .