The Athos departed Venezuela, South America, for the Citgo Asphalt Refinery in Paulsboro, N.J., on 26 November 2004, carrying approximately 13 million gallons of Bachaquero Venezuelan crude oil. At approximately 9:30 p.m. on 26 November 2004, tug operators assisting the Athos with docking at the refinery notified the U.S. Coast Guard (USCG) that the tanker was leaking oil. The vessel had struck several submerged objects while maneuvering through Anchorage #9 to its berth. Within minutes, the ship lost power and listed approximately 8 degrees to the vessel’s port side. Surveys of the river bottom following the incident found several objects in the area, including an 18,000-pound anchor, large concrete block, and pump casing. USCG determined that the anchor punctured the vessel’s number seven center cargo and port ballast tanks. The bulkhead between the cargo and ballast tanks was also damaged, allowing oil to migrate into the ballast tank and then into the river.

Initial reports indicated that the vessel released 30,000 gallons of the heavy crude oil. Later reports on 30 November suggested an increase in the volume spilled to a maximum potential of 473,500 gallons. The final estimate of 263,371 gallons became known after lightering of the remaining oil from the vessel and comprehensive analysis.