Some references to cars being scrapped, not ship wrecked:
1) (Bedford Basin) Highlights of the talk focused on the presence of former islands in the basin; archaeological sites of interest; the discovery of the Erg shipwreck - a wartime sinking in the basin with the loss of 19 lives; the discovery of the barge that caused the 1945 magazine explosion; 32 Volvo automobiles on the bottom; and many other fascinating aspects of the seabed.
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2) (Bedford Basin) 330 kHz sidescan sonogram from Bedford Basin, Halifax Harbour, collected with a neutrally bouyant and decoupled towfish, configured to minimize towfish motion. Image shows flat muddy seabed with linear anchor drag marks. The approximately 20 rectangular features on the seabed are discarded Volvo automobiles whose roofs have been colapsed before dumping. Known targets like these provide calibration for trials to improve sonar resolution.
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Of unrelated interest is the 1917 Halifax Disaster and the biggest non-nuclear explosion. It compared with 9-11 in terms of tragedy.
On December 6, 1917, two war ships, a Belgian relief ship, Imo, and a French ship carrying munitions, the Mont Blanc, fatally collided in Halifax Harbor. Incorrect signaling and misunderstanding between the two ships led the Imo to strike the side of the Mont Blanc. The Mont Blanc, which was carrying 400,000 pounds of TNT, 300 rounds of ammunitions, along with other explosive ingredients, caught fire and drifted closer into the city of Halifax. Before the fire could be put out, the Mont Blanc exploded creating the "biggest man-made explosion before the nuclear age". The explosion killed over 2,000 people and injured 9,000. The explosion caused $28 million in damage - 326 acres of the north-end of Halifax's waterfront had been destroyed.