The Cross Harbour ferry service, officially known as F4 Corss Harbour, is a commuter ferry service in Sydney, New South Wales. Part of the Sydney Ferries network, it is operated by Harbour City Ferries and services the Darling Harbour, Lavender Bay, Rose Bay, and Watsons Bay areas. The service replaced the entirety of the predecessor F4 Darling Harbour service and the Watsons Bay stopping pattern of the F7 Eastern Suburbs service. Emerald-class ferries and SuperCat ferries operate the service.

Prior to the introduction of the Cross Harbour route, service patterns on the Sydney Ferries network were often divided between wharves located west of Circular Quay, and wharves located east, with the exception of a short-lived service in the mid-1990s that linked McMahons Point and Rose Bay. The Cross Harbour service is a successor to the Darling Harbour ferry service, which existed in many iterations between the 1980s and 2017. The new serviced was unveiled by the New South Wales Government in a press conference held by Premier of New South Wales Gladys Berejiklian and Minister for Transport Andrew Constance on 27 March 2017.