The Greycliffe disaster occurred in Sydney Harbour (Australia) on 3 November 1927 when the harbour ferry Greycliffe and the Union Steamship Company mail steamer Tahiti collided. The smaller ferry was cut in two and sank with the loss of 40 lives, the deadliest incident on Sydney Harbour.
Greycliffe left Circular Quay, Sydney's main ferry terminus, at 4.15pm on Thursday 3 November 1927, with 120 passengers on board, including many schoolchildren returning home. The ferry stopped at Garden Island to pick up dock workers, and then resumed its journey on a course that would have taken it just north of the lighthouse near Shark Island. Its remaining intended stops were to be Nielsen Park, Parsley Bay, Central Wharf (near The Crescent), and Watsons Bay. On roughly the same course, however, was the liner operated by the Union Steamship Company of New Zealand's outward-bound transpacific Royal Mail Ship, the 7,585-ton RMS Tahiti, three times the size of Greycliffe. Greycliffe was ahead and to starboard of Tahiti.
At about half-way between Garden Island and Bradleys Head, Tahiti's bows struck Greycliffe midships on her port side. The small ferry was pushed around perpendicular to the large steamer's bow, and momentarily was pushed along. The ferry began to overturn, and was broken in two, and the steamer sailed through the ferry, which sank immediately. Passengers who were sitting outside had an easier chance to live, while those inside the two cabins—a ladies-only saloon, and a smoking room for men—were trapped. A number of other boats on the harbour witnessed the collision and rescued survivors from the water.
Several days later, smashed hull sections were towed to Whiting Beach near Taronga Zoo and divers looked for missing bodies. Seven of the forty killed were under the age of twenty, including a two-year-old boy who died along with his grandparents. Most of the victims came from the ferry's intended destination, the small Sydney suburb of Watsons Bay. Among the other victims was Millicent Bryant, who had become the first Australian woman to hold a pilot's license a few months earlier.