Sydney is the capital city of the state of New South Wales, and the most populous city in Australia. Located on Australia's east coast, the metropolis surrounds Sydney Harbour and extends about 70 km (43.5 mi) towards the Blue Mountains to the west, Ku-ring-gai Chase National Park, Marramarra National Park and the Hawkesbury River to the north and north-west, and the Royal National Park and Macarthur to the south and south-west.