The River Bollin is a significant tributary of the River Mersey in the north-west of England, flowing approximately 30 miles from its source in the Pennine foothills through Macclesfield and Wilmslow, passing beneath Manchester Airport before joining the Mersey section of the Manchester Ship Canal at Warburton. The river drains a landscape underlain by Triassic sandstone and mudstone geology, with superficial deposits of alluvium, river terrace material, and glacial till — characteristics that shape both the river's physical structure and its fishery. The Bollin flows through a mix of urban and rural settings, including steep-sided, wooded valleys with stretches of excellent natural physical shape. Decades of water quality improvement since the mid-1990s have transformed the Bollin from a near-lifeless waterway into a recovering and increasingly productive fishery, with migratory Atlantic salmon now confirmed spawning in its gravel beds.