Yassıören is a village in Devrek District, in Zonguldak Province, Türkiye. Yassıören lies at 433 m above sea level, in the Akçakoca Dağları mountains. It has 430 inhabitants. The nearest city is Devrek, 7.9 km to the south. Among the landmarks around are Heraclea Pontica (44 km) and Kozlu Dam (18.4 km). Among the natural features are Gökgöl Cave (19.1 km) and Çayırköy Cave (18.2 km).