The River Spey is one of the longest rivers in the UK at 107 miles, rising in Loch Spey and flowing northeast before entering the North Sea at Spey Bay. It sits on the edge of the Cairngorms National Park and is classed as the fastest flowing river in Scotland over its entire length, with a constant fast flow and some sections reaching grade 3. Unusually, the river increases in speed as it approaches the North Sea. The full route can be paddled from Loch Spey to Spey Bay, and is commonly divided into seven sections suitable as single day trips or combined into multi-day expeditions of three to five days.

Popular put-ins include Spey Bridge above Newtonmore, Loch Insh (with access at the Watersports Centre or Alvie Church), and Advie Bridge. The river passes through or near Newtonmore, Kingussie, Aviemore, Boat of Garten, Grantown-on-Spey, Aberlour, and Fochabers before reaching Spey Bay. Notable rapids include the Blackboat Rapid (known as "the Washing Machine") and Knockando, which serves as a whitewater slalom training site with basic changing facilities and toilets on site.

The upper stretch near Newtonmore can be shallow and technical at low water, while higher levels can cause overhanging trees to become a greater hazard. The first section below Loch Insh in particular carries significant tree hazard and should not be taken lightly. At higher flows some larger rapids wash out, while low water exposes protruding rocks. The river has a large catchment draining the Cairngorms plateau, which generally ensures reasonable water levels throughout the year.

Under Scotland's Land Reform Act, there is a public right of navigation on the Spey, which is also designated as a Core Path within the Cairngorms National Park and Highland Council boundaries. Paddlers are expected to respect anglers' rights and make reasonable efforts to minimise disturbance. Organisations and clubs using the river are asked to contribute to an Access Fund. Those organising formal events should liaise with relevant Local Authority Access Officers.

Wildlife along the river includes wild salmon, ospreys nesting near Loch Insh, sand martins, and birds of prey. The river corridor passes through the heart of Speyside whisky country, with numerous distilleries accessible from the water. Wild camping on river islands is possible along the route, and formal campsites are also available at various points.