Sydney Ferries service being operated on the Parramatta River by PS "Surprise" from 1831. Cross-harbour services began in 1842 and this business grew to such an extent that a public company was formed, the North Shore Steam Ferry Co. Ltd. in 1878. In 1900, the North Shore company was reincorporated as Sydney Ferries Limited (SFL), which progressively took over most other harbour ferry services (except notably the Manly service operated by the Port Jackson & Manly Steamship Company), and became the world's largest ferry operator by fleet size. After the Sydney Harbour Bridge opened in March 1932, SFL patronage dropped almost overnight,
Sydney Harbour Tunnel to Sydney Harbour. A trench was dredged before the arrival of the IMTs and then the IMTs were lowered into the trench by a system of pontoons and control towers. After the IMTs were in place the trenches were backfilled and then a rock armour was placed over the top to protect the units against marine hazards, such as anchors or sinking vessels. The land tunnels were constructed by a combination of driving and cut-and-cover techniques, designed to be strong enough to withstand the impact of earthquakes. The northern end pylons of the Sydney Harbour Bridge were altered to allow