"International Tanker Owners Pollution Federation reporting about 7000 tonnes of crude oil spilling from tankers into oceans in 2017 alone."
".. explosion on the Deepwater Horizon offshore drilling rig on 20 April 2010 and subsequent release of approximately 4.9 million barrels of crude oil into the Gulf of Mexico."
According to this site (https://www.reference.com/science/much-barrel-oil-weigh-b29e...) "In order to get a metric tonne of oil, one would need about 7.33 barrels of oil."
7000 tonnes ~ 51,310 barrels
4.9 million barrels ~ 668,485 tonnes