A Fin whale was seen of Sydney on 4 November 2011. It appears to be the first record for NSW.
It was clearly a rorqual whale (i.e. a baleen whale in the genus Balaenoptera). It was longer and slimmer than a humpback, with a long flat back, a big falcate, back-swept dorsal fin, a column-shaped blow and a brown-grey (not black-grey) colour. There are only a couple of options. Obviously it was not a Blue Whale, even a young small one, because it was the wrong colour, it had a big fin, and it was not sprawling in girth. That leaves only Fin and Sei whales in the right size range. Sei Whale blows and presents a very flat profile with a long flat back, and it is so flat that the fin appears before the blowholes sink. Minke is like a wheel with a fin on the top, and the blow is almost never visible. Fin Whales break the surface with a long head, the columnar blow appears, the head goes down as the long flat back appears, and the big falcate dorsal fin appears well after the head has sunk and shortly after the blow has dissipated.
This is is very rare off the east coast of Australia , and I don't know of any previous records from 30 years of regional pelagic trips