Flat Rock Beach is a small, south-facing beach on Middle Harbour, in Garigal National Park. The sand is deposited on a rock shelf that pokes through in places, forming interesting sculptures. The beach is frequented by walkers and boaters enjoying their day by the water. The beach can be accessed by a bush track from the end of Killarney Drive, Killarney Heights. Historically, the beach was a popular picnic area and serviced by a ferry in the early 1900's. Today, there are no facilities, but some shade is provided by the trees at the back of the beach.