The Annan rises on Annanhead Hill above the Devil's Beef Tub — a glacially overdeepened valley in the Southern Uplands famous from Walter Scott — and runs roughly 76 kilometres south and southeast to Solway Firth at Annan. The catchment is about 1,400 square kilometres of older sedimentary rock; the geology is Silurian greywacke and shale surrounding soft Carboniferous rocks of the central basin, creating the physical foundation for a moderate-responding spate river. The middle reaches through Annandale are pool-riffle on well-sorted cobble and gravel, with extensive point-bar development and the character of a Scottish border river — rural, rhythmic, and belonging to its valley. The river is less famous than some of its neighbours, which is part of its charm. Watch the shifting character at the junction of the Kinnel Water — a significant left-bank tributary — and note how the wading changes from secure cobble to the occasional soft-banked section after a spate.

Wading: Soft silt sand drapes on lower reach point bars

Summer-autumn runs (June–September), nocturnal pattern in peak season