From the deliberate Gulf War release to the Deepwater Horizon blowout, these are the largest spills on record — with volumes, causes, and the regulations each disaster produced. Notably, the famous Exxon Valdez barely makes the list by volume; its legacy is regulatory.
| Incident | Year | Location | ≈Volume | Notes |
|---|---|---|---|---|
| Gulf War spill | 1991 | Persian Gulf, Kuwait | ≈240–336M gal | Deliberate wartime release by retreating Iraqi forces — the largest spill ever |
| Deepwater Horizon | 2010 | Gulf of Mexico, US | ≈210M gal | BP's Macondo well blowout; 87 days to cap, 11 workers killed, ~$65B in costs |
| Ixtoc I | 1979 | Bay of Campeche, Mexico | ≈140M gal | Pemex exploratory well blowout; flowed for 9 months |
| Atlantic Empress | 1979 | Off Trinidad & Tobago | ≈88M gal | Two fully laden supertankers collided in a storm — the largest tanker spill |
| Fergana Valley | 1992 | Uzbekistan | ≈88M gal | Onshore well blowout — the largest inland spill |
| Nowruz Field | 1983 | Persian Gulf, Iran | ≈80M gal | Platform collision then wartime damage during the Iran–Iraq war |
| ABT Summer | 1991 | Off Angola | ≈80M gal | Loaded tanker caught fire and sank in open ocean |
| Castillo de Bellver | 1983 | Off South Africa | ≈79M gal | Tanker fire and breakup near Saldanha Bay |
| Amoco Cadiz | 1978 | Brittany, France | ≈69M gal | Steering failure drove the tanker onto rocks; devastated 200 miles of coast |
| Exxon Valdez | 1989 | Prince William Sound, US | ≈11M gal | Far from the largest, but ecologically infamous — led to the US double-hull mandate (OPA 90) |
Volumes are widely cited estimates — precise figures for the largest events remain disputed. Related: oil tankers · offshore drilling · live tanker map.
The 1991 Gulf War spill, when retreating Iraqi forces deliberately released an estimated 240–336 million gallons (6–8 million barrels) into the Persian Gulf. The largest accidental spill is Deepwater Horizon (2010), at about 210 million gallons over 87 days.
Deepwater Horizon spilled roughly 20 times more oil (~210M vs ~11M gallons). Exxon Valdez remains iconic because it struck a pristine, enclosed Alaskan sound where oil persisted for decades — proof that location and ecology matter as much as volume. It also produced the 1990 Oil Pollution Act and the double-hull tanker requirement.
Dramatically better at sea: large tanker spills fell from about 25 per year in the 1970s to fewer than two per year in the 2010s, thanks to double hulls, traffic separation and inspection regimes. The remaining large-spill risk has shifted to wells (blowouts like Deepwater Horizon) and to aging "shadow fleet" tankers operating outside Western insurance standards.
A hierarchy of imperfect tools: containment booms and skimmers recover a minority of surface oil; controlled burns remove more in calm conditions; chemical dispersants break slicks into droplets for microbes to degrade (trading surface impact for water-column exposure); and shoreline cleanup ranges from pressure-washing to leaving sensitive marshes to recover naturally. Recovery rates above 20–30% of spilled volume are considered good.