On July 23, 2006, she was en route from Japan to Vancouver, British Columbia, Tacoma, Washington, and Port Hueneme, California, with a cargo of 4,812 vehicles. During a transfer of ballast water, she lost stability and developed an 80-degree list to port. There were reports of a large wave striking the vessel during the ballast transfer, but it is unknown what effect this had on her loss of stability. On July 24, the United States Coast Guard successfully rescued the 23 crew members. 
Approximately 4,700 of the vehicles were Mazdas, with about 60% of these being the 2007 Mazda3s and 30% being Mazda CX-7 crossover SUVs. The remaining Mazdas are RX-8s and MX-5s. About 100 of the vehicles were not Mazdas, but the exact make of those has not been disclosed.  They are said to be valued at US$117 million. Mitsui OSK is executing a salvage operation in order to recover as many assets as possible. 
On July 31, 2006, Marty Johnson slipped and fell to his death as the salvage team was preparing to return from the Cougar Ace to the tug Sea Victory. Johnson was a forty-year old resident of Seattle, Washington and employee of the Titan Salvage salvage team from Seattle, Washington.
While initially adrift, the ship was later towed by tugboats to Unalaska Island, where it was moored next to Icicle Seafoods buoys as it was righted. On August 25, 2006 the newly upright vessel was put under tow to Portland, Oregon for inspection and repair.
Mazda officials reported little to no damage to the vehicles onboard despite the ship listing nearly 90 degrees for over a month.  However, according to the US Coast Guard, 41 vehicles broke loose and shifted, and the few public pictures from inside the ship do show severe damage to at least some cars.  
On September 11, 2006, one day before the Cougar Ace arrived in Portland to begin unloading, Mazda USA announced that none of the Mazda cars aboard will be sold as new vehicles.  Mazda USA published a list of VINs for the affected Mazda vehicles on the www.MazdaUSA.com website.
On December 15, 2006, Mazda announced that all vehicles on the Cougar Ace will be scrapped. "