What river is XXX a tributary of?
Hawkesbury River
The Hawkesbury River has its origin at the confluence of the Nepean River and the Grose River, to the north of Penrith and travels for approximately 120 kilometres (75 mi) in a north--easterly and then south--easterly direction to its mouth at Broken Bay, about 15 kilometres (9.3 mi) from the Tasman Sea.
Broken Bay