Río Grande is the reason serious sea-trout anglers eventually make the journey south. Sea-run browns push up from the South Atlantic through steppe country into a river that offers little visual romance and everything that matters below the surface: fish running well into double figures, some considerably larger, taking flies with the deliberate weight of migratory fish rather than the nervous take of a resident trout. Tactics here are specific — Sunray Shadows, Stoat's Tails and Collie Dogs fished across and down on sink tips, worked through named beats at dawn and dusk when fish move and light is low. Wind off the pampa is constant and must be read as carefully as the water. This is lodge-controlled fishing almost without exception; access, boats and beat rotation are arranged well in advance, and a rod here is booked, not improvised. Expect discipline, cold hands, and fish that justify both.

• Alluvial