River Tay River Tay The River Tay () 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 (), 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
Inner Tay Estuary Inner Tay Estuary The Inner Tay Estuary, the inner, western part of the Firth of Tay, stretching from the Tay Railway Bridge in the east to the Queen's Bridge over the River Tay in Perth and the bridge in Bridge of Earn on the River Earn. The estuary is one of the largest in eastern Scotland and is up to 2.5 km wide. The estuary consists primarily of inter-tidal sand and mud flats that extend seaward out to the main channel of the estuary, the majority of which lie on the northern shore. Landward of these are saltmarsh and "Phragmite"s