The Picos de Europa National Park presents a wealth of flora and fauna. On the lower levels grasslands with oaks and hazel trees coexist, together with maple, linden, ash, chestnut and walnut trees, and an undergrowth of heather, brambles and other shrubs.

The Atlantic forest type is predominant throughout, although in some areas, including the gorges of the rivers Sella, Cares and Deva, Mediterranean climate conditions occur with the corresponding vegetation such as oak, strawberry trees and laurels. The sub-alpine level is rich with the colours of the beech forest. As the altitude increases beeches are gradually replaced by juniper, heather, blueberry, gorse and broom. Finally, on the highest peaks, only small plants and shrubs survive.