The River Tay (Tatha in Scottish Gaelic) is Scotland's longest river at 117 miles (188km) and the UK's 7th longest overall. It carries the highest water volume discharge of any river in Scotland, averaging 100 cubic metres per second, and remains notably high in flow for much of the year even when other rivers have dropped. The river system begins on the flanks of Ben Lui and flows east across the Highlands before becoming tidal at Perth, eventually emptying into the North Sea via the Firth of Tay south of Dundee.

The most common put-in for multi-day expeditions is at Killin on Loch Tay, which is 24km long and typically takes two days to cross. The river proper begins at Kenmore, where the outflow of Loch Tay marks the start of moving water. From Kenmore downstream to Aberfeldy, the river offers grade 1–2 rapids suitable for developing whitewater skills such as breaking in and out, ferry gliding, and wave surfing. The standout technical feature is Grandtully Rapids, home to Scotland's national whitewater training venue, rated a solid grade 3. Depending on water levels, paddlers may choose to portage here. Further downstream toward Perth, notable features include Campsie Linn, Stanley Mills, and Thistle Brig. The river becomes tidal at Perth, and the tidal section extending to the Firth of Tay contains fast-moving water that requires experience and careful timing to navigate safely.

For shorter trips, the Perth city section is popular. A small slipway on the right bank just upstream of the railway bridge serves as a convenient launch point. The route around Moncrieffe (Friarton) Island covers approximately 6.4km and is rated easy to moderate depending on tide and water level. The tidal influence means conditions can vary significantly, and tandem paddling is recommended for less experienced paddlers in this section. The Broughty Ferry section near Dundee offers sea and touring kayaking along the Firth of Tay coast, with views of the 16th-century Broughty Ferry Castle and opportunities to observe seabirds, seals, and occasionally dolphins.

The river passes through diverse Perthshire countryside, with the Ben Lawers mountain range visible to the north of Loch Tay. Ancient Crannogs (historic water-based dwellings) are visible along the loch. Wild camping along the riverbanks is a common feature of multi-day expeditions on the upper river.