Cabbage Tree Bay Aquatic Reserve, Marine reserve in Manly, Australia.

Cabbage Tree Bay Aquatic Reserve is a 17-hectare no-take marine protected area on the north side of North Head at Manly, Sydney. It lies between Manly Beach to the northwest and Shelly Beach to the east, and its habitats include a sandy beach, a rocky shore, reefs, seagrass meadows and kelp forests.

The rocky shore of Cabbage Tree Bay was designated an Intertidal Protected Area from 1993 to 2002. In 2002 the bay became a no-take aquatic reserve, managed by the New South Wales Department of Primary Industries. The reserve covers 17 hectares on the northern side of North Head.

The reserve lies in the country of the Gayamaygal, part of the Eora nation, whose traditional lands take in the Manly coastline. The name Cabbage Tree Bay refers to the cabbage tree palms once common on these shores. Today the bay is used for swimming, snorkelling and shore dives, and the no-take rule, in force since 2002, keeps the reef and seagrass habitats intact for visitors.

The reserve runs from Manly Beach to Shelly Beach, with entry points at both sandy ends and a rocky shore along the south. Swimming and diving are allowed; fishing, collecting or damaging any organism, dead or alive, is not. The site is managed by the NSW Department of Primary Industries.

The waters here contain over 160 fish species and around 50 types of marine invertebrates. In spring and summer, tropical species arrive via ocean currents, making for unexpected sightings at this southern location.