Back in October 2016 I spent a few days with my brothers cruising around the Hawkesbury River on a boat, previously called the Dyarubbin by the Darug people who inhabited upper reaches of the river before colonial times while the area we were cruising was traditionally owned by the Garigal people.
The broad expanse of the river is bordered by steep sandstone hills so rugged that even now mail deliveries and access to some settlements is done by boat because it is too difficult and uneconomic to cut roads through the terrain. In the early days of the colony produce from the rich alluvial river flats further up river were transported from around Windsor, down the Hawkesbury into the open ocean and then to Sydney- more than 160 km and several days by boat as opposed to roughly 42 km as the crow flies over land. Most of this lower section of the river is National Park and remains “untouched” making it difficult to realise how close to a major city we were.
See Dictionary of Sydney and Hawkesbury River.