The Plym rises in the marshy upland of Plym Head on southern Dartmoor, around four hundred and fifty metres up, and runs some thirty kilometres south-west — gathering the Meavy at the Dewerstone — down to Plymouth Sound. The upper river is moorland spate water: peat-tinged, acidic and quick, tumbling over a granite bed past the antiquities and old mining remains of the moor before it drops through wooded valley toward the tide. The water is clean and fast off the granite, rising and falling hard with the weather. The Plym has one of the latest salmon runs in the country — the main push coming in November and December — with a scatter of sea trout in from May. The character is steep, boulder-strewn freestone with wild brown trout above. Wading is slick granite-boulder work, uneven under the trees and no place to be careless in a rising river.

Wading: Slick boulders, fast to rise