High Quality Content by WIKIPEDIA articles! Amoco Cadiz was a very large crude carrier (VLCC), owned by Amoco, that ran aground on Portsall Rocks, 5 km (3.1 mi) from the coast of Brittany, France, on 16 March 1978, and ultimately split in three and sank, all together resulting in the largest oil spill of its kind in history to that date.