This midnight-blue crater lake, enclosed by a fuzz of pine trees, lies 6km southwest of Besse. Blasted out of the earth by a volcanic explosion nearly seven millennia ago, today it attracts trout fishers and walkers; the trail around the shore takes less than an hour. There's pedalo rental in summer (half-/full day €5.50/10). Winter, when the lake has a frosty halo, is even more beautiful.
There's free parking nearby but at the height of summer you may have to fight for a space.