The hills above Osiglia are covered in mature sweet chestnut, a tree that for centuries was a staple food in the upper Bormida valley. Chestnuts were ground into flour, made into polenta, and roasted in autumn — and they remain a local pride, celebrated at a small village festival in October.
The woods are good walking country in their own right. Two enormous chestnut trees, with girths of nearly three and five metres, draw the occasional curious visitor and are signposted from the village. A network of waymarked paths links Osiglia to neighbouring villages of Bormida and Calizzano through the woods.