Sydney Harbour, off Garden Island. 23 October 2017.
Vessel at 33°51'25.15" S 151°13'55.34" E
In background HMAS HOBART D39

See RAN website:
http://www.navy.gov.au/hmas-stuart-iii

Stuart is a long-range escort capable of air defence, surface and undersea warfare, surveillance, reconnaissance and interdiction. The ship can counter simultaneous threats from aircraft, surface vessels and submarines.