It caused considerable damage to wildlife in the Persian Gulf especially in areas surrounding Kuwait and Iraq. Estimates on the volume spilled range from 42 to 462 million gallons; the slick reached a maximum size of 101 by 42 miles and was 5 inches thick. Despite the uncertainty surrounding the size of the spill, figures place it 5 to 27 times the size (in gallons spilled) of the Exxon Valdez oil spill, and more than twice the size of the 1979 Ixtoc I blow-out in the Gulf of Mexico.
According to a study sponsored by UNESCO, Bahrain, Iran, Iraq, Kuwait, Oman, Qatar, Saudi Arabia, the United Arab Emirates and the United States, the spill did little long-term damage. About half the oil evaporated, a million barrels were recovered and 2 million to 3 million barrels washed ashore, mainly in Saudi Arabia.
On January 21, 1991, Iraqi forces opened valves at the Sea Island oil terminal and dumped oil from several tankers into the Persian Gulf. The apparent strategic goal was to foil a potential landing by U.S. Marines. The oil moved southward, ending up on the north coast of Saudi Arabia, endangering the fragile intertidal zones and mangrove forests and destroying wildlife habitats. 
The immediate reports from Baghdad said that American air strikes had caused a discharge of oil from two tankers. Coalition forces determined the main source of oil to be the Sea Island terminal in Kuwait. American airstrikes on January 26 destroyed pipelines to prevent further spillage into the Persian Gulf. Several other sources of oil were found to be active: tankers and a damaged Kuwaiti oil refinery near Mina Al Ahmadi, tankers near Bubiyan Island, and Iraq's Mina Al Bakr terminal.