The Blue Mountains is a mountainous region in New South Wales. It borders on Sydney's metropolitan area, its foothills starting approximately 50 kilometres west of the state capital.The area begins on the west side of the Nepean River and extends westward as far as Coxs River. Geologically, it is situated in the central parts of the Sydney basin.
Consisting mainly of a sandstone plateau, the area is dissected by gorges up to 760 metres deep.The highest point of the range is Mount Werong at 1,215 metres above sea level.
A large part of the Blue Mountains is incorporated into the Greater Blue Mountains Area World Heritage Site, consisting of seven national park areas and a conservation reserve.
