Hobart sits astride the wide tidal Derwent, and for most of its history a single span did the work of joining its two halves. By the 1950s the old floating Hobart Bridge was failing under the load. The opening of Hobart Airport at Cambridge in 1956 sent the eastern shore into a building boom; within a year the airport ranked fifth busiest in the country, and the cars kept coming. The state's Department of Public Works commissioned a new crossing in 1956, settling on a long concrete girder bridge of twenty-two spans, its navigation arch rising 60.5 metres above the water to let cargo ships pass beneath. It opened in stages through 1964 and was formally inaugurated on 29 March 1965 by Prince Henry, Duke of Gloucester. For a decade it was simply the bridge, the thing everyone drove across without a second thought.

The danger had been named in advance. As early as 1958, engineers raised concerns that the concrete piers were vulnerable to a ship strike, and Premier Eric Reece pushed those objections aside in parliament, favouring the cheaper design over a slightly costlier suspension bridge. Seventeen years later the warning came true in the worst possible way. The court that examined the disaster found the Lake Illawarra's master at fault: the ship was off course, partly from a strong tidal current but also from simple inattention, and it had tried to thread an eastern span instead of the central navigation arch. A late order of full speed astern came too late, and all control was lost. After the disaster, a marine pilot service was introduced for ships moving up the Derwent, a safeguard that should have existed all along.

For the people of Hobart's eastern suburbs, the collapse turned a two-minute drive into an ordeal. With the bridge gone, reaching the city centre meant a 50-kilometre detour upriver to the next crossing at Bridgewater. The only nearby alternative was the Risdon Punt, a cable ferry that managed just eight cars a crossing, hopelessly inadequate for a suburb of commuters. Small passenger ferries were pressed into service almost overnight, joined by elderly vessels loaned from New South Wales. Not until December 1975 did a hastily built Bailey bridge restore a real road link. The full repair took two and a half years and cost roughly 44 million dollars. When the Tasman Bridge reopened on 8 October 1977, it returned with a fifth, reversible lane and a hard lesson learned. A second crossing, the Bowen Bridge, was later built upstream so that the city would never again hang on a single thread.

The Lake Illawarra is still down there. The ship lies on the riverbed between piers 17 and 19, under about 35 metres of water and a scatter of fallen concrete, its 10,000 tonnes of zinc concentrate sealed in the hold where they came to rest in 1975. The wreck poses no hazard to smaller boats and has become a quiet pilgrimage for divers. In 2019 the Tasmanian University Dive Club shared the clearest footage ever taken of it, made possible by cleaner, less silty water after years of improved stormwater management. In 2022 the CSIRO and engineers from Jacobs built the first complete 3D model of wreck, bridge, riverbed and shore, mapping the ship's bow angled 45 degrees toward midstream. Above the water the bridge has moved on, strung now with nearly two thousand programmable LEDs that glow for everything from local sports teams to days of mourning. Below it, the river keeps its memorial.