Sydney occupies a coastal basin on the southeastern coast of Australia. It is bordered by the Tasman Sea (Pacific Ocean) to the east, the rugged, forested valleys of the Blue Mountains to the west, the Hawkesbury River to the north, and the Woronora Plateau to the south.
The city's physical geography is defined by its deep, submerged river valleys (rias), the most famous of which is Sydney Harbor. The broader metropolitan area spans two primary geographic regions: the Cumberland Plain, a relatively flat and undulating region to the west and south, and the Hornsby Plateau, a hilly, sandstone region situated to the north of the harbor.
Natural resources in the immediate region are limited mostly to sandstone—which historically provided building materials for the city's early architecture—and rich ecosystems that support localized fishing. The city is enveloped by extensive natural bushland and several national parks, including the Royal National Park (the second oldest national park in the world) to the south.
