The Big Hole runs out of the high, wide valley that gives it its name — the 'big hole' the old trappers meant, a broad sweep of hayfield and willow under the Pioneer Mountains — and threads down through Wisdom and Wise River toward its meeting with the Beaverhead. It's a true freestone, snowmelt-fed and unregulated, swinging from braided meadow channels up top to a rocky canyon lower down. The upper river is the last refuge of the fluvial Arctic grayling in the lower forty-eight, a fish that has no business still being there and is. The bed is rounded freestone cobble, the lies in the riffles, undercut banks and willow corners. The river runs cold and high through June and can drop worryingly low and warm in a dry August. Wading is straightforward on cobble, with the usual care where the canyon pushes the water.

Wading: Low warm water late summer, pushy in the canyon