The Puelo gathers itself in Argentina, out of its own namesake lake, and crosses into Chile as one of northern Patagonia's biggest and wildest rivers, running down its own valley past Llanada Grande and Lago Tagua Tagua to the Reloncaví fjord. It carries serious glacial-volcanic volume even in low water, and that weight of current shapes the fishing — streamers and sculpin patterns worked deep through braided channels and back eddies, with dry-dropper rigs coming into their own where the current softens. Brown and rainbow trout share the river with chinook salmon, and a raft or drift boat makes far more of the water fishable than wading ever could. It's remote, unhurried country, best fished with a guide who knows this season's channel.

• Volcanic glacial