After leaving Loch Spey the river gathers numerous burns in the Corrieyarack, Sherramore and Glenshirra Forests. The first sizeable tributary is the Markie Burn which drops out of Glen Markie to the north to enter the waters of Spey impounded behind the Spey Dam. A further mile downstream the River Mashie enters from Strath Mashie to the south. The River Truim enters on the right bank a couple of miles above Newtonmore and the Highland Calder enters from Glen Banchor on the left bank at Spey Bridge at Newtonmore. At Kingussie the Spey is joined on its left bank by the Allt Mor which runs through the town and 1.5 miles downstream it is joined by the River Tromie which enters on the right bank. The sizeable River Feshie joins on the right bank at Kincraig and the River Druie does likewise at Aviemore. Several miles downstream the River Nethy joins from the east near Nethy Bridge and the River Dulnain originating in the Monadhliath contributes a considerable flow from the west near Dulnain Bridge. Between Grantown-on-Spey and Craigellachie, the Burn of Tulchan and Allt a Gheallaidh join from the west whilst the Spey's most important tributary, the River Avon joins from the east. The Allt Arder and Knockando Burn also join from the west near Knockando.
