The Lison starts in the most theatrical fashion of any trout stream in France — as a full-sized river vaulting out of a cave mouth at Nans-sous-Sainte-Anne, clear as vodka and cold enough to make your wrist ache when you dip it in. Within fifty metres it's a proper river with proper fish. It joins the Loue after twenty-odd kilometres of mostly wooded, mostly wadeable limestone water, and along the way it holds wild brown trout and some of the most obliging grayling in the Jura. Obliging, that is, until they've been cast over once. After that they revert to being grayling. The upper river fishes like a spring creek — small flies, clean presentation, fish that sit pinned to the bottom between rises. The lower river opens into glides you can cover with a nymph rig and a reasonable expectation of a fish on every other run.

• Limestone