The Northern Beaches is a region within Northern Sydney, in the state of New South Wales, Australia, near the Pacificcoast. This area extends south to the entrance of Port Jackson (Sydney Harbour), west to Middle Harbour and north to the entrance of Broken Bay. The area was formerly inhabited by the Garigal or Caregal people in a region known as Guringai country.
Cabbage Tree Aquatic Reserve covers approximate 20 hectares including the entire bay, the rocky shores and beaches from the southern end of Manly Beach to the Northern end of the Shelly Beach Headland.
Cabbage Tree Bay was declared a No Take Aquatic Reserve in March 2002. As it is so highly protected it makes this reserve a popular dive and snorkeling spot with a huge variety of marine species and several types of habitats.