Dangar Island lies in the throat of the Hawkesbury River, about 50kms north of Sydney.
I took an Intercity train from Central to the Hawkesbury River station at Brooklyn. There I caught the ferry that services the settlements along the Hawkesbury. On the island there is a solar powered buggy to assist elderly residents from the wharf up the hill. Other transport is by dinghy, bicycle or wheel-barrow.
I heartily recommend Kate Grenvilles's 'The Secret River'(2005) and 'Searching for the Secret River'(2006) Text Publishing, Melbourne.