Great Mackerel Beach is a suburb about 43 kilometres north of the Sydney central business district, from 2016 in the local government area of Northern Beaches Council, Sydney, New South Wales, Australia, formerly part of Pittwater Council. It is on the western shores of Pittwater in Ku-ring-gai Chase National Park, beside Currawong Beach, and near Coasters Retreat and Palm Beach.The resident population was 50 at the 2021 census; the median age was 57, with an average of 0.3 children per family and an average of 1.7 people per household. The population was 36 at the 2016 census, 301 at the 2011 census, and 103 in 2006. As of 2021 there were 111 private dwellings, with many people not listed as residents occupying properties during school holidays and weekends. Great Mackerel Beach is frequently referred to as Mackerel Beach or [Great] Mackeral Beach, although the spelling "Mackerel" is becoming standard.

The Northern Beaches Council is a local government area located in the Northern Beaches region of Sydney, in the state of New South Wales, Australia. The council was formed on 12 May 2016 after the amalgamation of Manly, Pittwater, and Warringah councils.