The 14 Biggest Oil Spills in History

The global thirst for crude oil for transportation, heating, plastic production, and the like have resulted in thousands of oil spills over the years. According to data from the National Oceanic and Atmospheric Administration, which tracks spills throughout the U.S. and abroad, almost 200 incidents have occurred annually for many years running.

Spills can be as small as a dozen gallons or as big as several million gallons. The largest oil spills can wipe out entire species and make an ecosystem uninhabitable for decades. Oil spills come with environmental consequences that impact animals and people alike.

It's impossible to predict just how much damage a spill can cause based solely on number of gallons. Take the Exxon Valdez oil spill of 1989 for example. Although the volume of that spill seems minor compared to others (11 million gallons versus the Persian Gulf oil spill's 380 to 520 gallons), it was widely considered to be the worst oil spill in history before 2010's Deepwater Horizon incident. That's because the oil washed onto 1,300 miles of Alaskan coastline and had a catastrophic impact on wildlife and the environment. Volume plays just a small role in the impact.

Here are 14 of the biggest oil spills in history and their oft-ongoing impact on marine environments.

1. Persian Gulf Oil Spill

The worst oil spill in history was the Persian Gulf oil spill, also called the Arabian Gulf or Gulf War oil spill because it was used as a defense tactic. In January of 1991, Iraqi forces attempted to prevent American soldiers from landing on their shores by opening valves at an offshore oil terminal and dumping oil from tankers. The oil resulted in a four-inch-thick oil slick that spread across 4,000 square miles of the Persian Gulf.

Oil continued to spill into the Gulf at a rate of 6,000 barrels a day for three months. By the end of July, most of it had been removed even though wartime conditions hindered cleanup efforts. Oil continued to seep into the water from coastal sediments for a year.

2. BP Deepwater Horizon Oil Spill

The BP Deepwater Horizon oil spill is officially the largest accidental spill in world history. It began when an oil well a mile below the surface of the Gulf of Mexico blew out, causing an explosion on BP’s Deepwater Horizon rig. The explosion killed 11 people.

BP made several unsuccessful attempts to plug the well, but oil flowed at a rate as high as 2.5 million gallons a day until the well was capped on July 15, 2010. Oil gushed from the broken well for more than 85 days, oiled 572 miles of Gulf shoreline, and killed hundreds of birds and marine life. The long-term effects of the oil and the 2 million gallons of dispersant used on this fragile ecosystem remain unknown, but experts say they could devastate the Gulf coast for decades to come.

3. Ixtoc I Oil Spill

Like the BP Deepwater Horizon fiasco, the Ixtoc I oil spill didn't involve a tanker but rather an offshore oil well. Pemex, a state-owned Mexican petroleum company, was drilling an oil well when a blowout occurred. The oil ignited, and the drilling rig collapsed. Oil began gushing out of the well into the Gulf of Mexico at a rate of 10,000 to 30,000 barrels a day for almost an entire year before workers were finally able to cap it.

The oil from this spill swept onto sandy beaches and into mangroves, coastal lagoons, and rivers. It had a tremendous impact on marine life, including octopuses, Kemp's ridley turtles, and shrimp.

4. Atlantic Empress Oil Spill

The Greek oil tanker Atlantic Empress was caught in a tropical storm off the coast of Trinidad and Tobago when it collided with another tanker, the Aegean Captain. The Atlantic Empress caught fire, killing 26 sailors, and the Aegean Captain began leaking oil. It continued to leak oil gradually over the next few days, even as it was being towed to Curacao.

The fiery Atlantic Empress was towed toward the open sea to give vessels easier access to fight the fire. It sank into the deep water slowly over the following two weeks. After it capsized, the remaining cargo solidified.

5. Komi Pipeline Oil Spill

A poorly maintained pipeline caused this massive oil spill in the Komi province of Russia. The pipeline had been leaking for eight months, but a dike contained the oil until sudden cold weather caused the dike to collapse. Millions of gallons of accumulated oil were released and spread across 170 acres of streams, fragile bogs, and marshland.

Annual flooding threatened to wash the oil into the Kolva and Pechora Rivers, which empty into the Arctic Ocean. Earthen dams were constructed to contain the spill, but the next spring, they failed under the pressure of thawed ice. The oil released into the Kolva River as a result made it uninhabitable for aquatic life.

6. Castillo de Bellver Oil Spill

The Castillo de Bellver, a Spanish tanker traveling from the Persian Gulf to Spain, caught fire 70 miles north west of Cape Town in 1983. It drifted into the open sea, ultimately breaking in two 25 miles off the coast. The ship’s stern sank along with the estimated 100 million tons of oil it was carrying. The bow section was towed and deliberately sunk later.

The oil drifted toward the shore at first but quickly changed direction with the wind. After the spill, some 1,500 oil-affected gannets were collected from a nearby island. Within the first 24 hours, there were reports of black rain over crops and sheep grazing lands, but the impact of the spill were considered to be overall negligible. No cleanup was conducted save some dispersant spraying.

7. ABT Summer Oil Spill

This ABT tanker ship detonated inexplicably off the coast of Angola, discharging massive amounts of oil into the ocean. Five of the 32 crew members on board died in the incident. A large slick covering an area of 80 square miles spread around the tanker and burned for three days before the ship sank on June 1, 1991. Subsequent efforts to locate the wreckage were unsuccessful.

The environmental impact of the spill is believed to have been minimal considering it occurred in the high seas, where waves can break up the oil.

8. Amoco Cadiz Oil Spill

The Amoco Cadiz—a "very large crude carrier" or VLCC—was caught in a winter storm that damaged the ship’s rudder. The ship put out a distress call, and although several ships responded, none were able to prevent the ship from running aground. Its steering wheel failed, causing the vessel to collide with the Portsall Rocks off the coast of Brittany.

The supertanker broke in half, sending a reported 194 million gallons of oil into the English Channel. The resulting slick spanned 18 miles wide and 80 miles long. Studies following the accident reported "massive mortalities" among intertidal crabs, nereid worms, molluscs, and limpets. More than 3,200 dead birds representing 30 species were recovered. The environmental affects of the Amoco Cadiz lasted decades.

9. MT Haven Tanker Oil Spill

This oil tanker exploded and sank off the coast of Italy, killing six people and leaking its remaining oil into the Mediterranean for 12 years. The source of the explosion was thought to be the ship’s poor state of repair. Supposedly, the Haven was scrapped after being hit by a missile during the Iran-Iraq War, but was put back into operation.

Authorities attempted to tow the vessel to the coast to reduce the affected area, but the bow broke in the towing process, and the ship sank by April 14. Following the spill, fisheries along the coast of France and Italy suffered for decades from the pollution.

10. Odyssey Oil Spill

The Liberian tanker Odyssey was carrying 132 metric tons of crude oil when it became caught in an Atlantic storm. Having endured 25-foot waves and 50-mph winds, an explosion occurred on board and split the ship in two. More than 40 million gallons of oil spilled out of the vessel, covering an area of 30 square miles about 700 nautical miles off the coast of Newfoundland.

No cleanup efforts were made because the spill occurred so far from shore. The spill reportedly had a large effect on the local krill population, which impacted the food chain for years.

11. The Sea Star Oil Spill

The South Korean supertanker Sea Star collided with a Brazilian tanker, the Horta Barbosa, off the coast of Oman on the morning of December 19, 1972. The vessels caught fire after the collision and the crew abandoned ship. Although the Horta Barbosa was extinguished in a day, the Sea Star sank into the Gulf on December 24 following several explosions.

No response actions or cleanup efforts were implemented following the spill, and its impact on wildlife is unknown.

12. Nowruz Oil Field Spill

The Nowruz Oil Field spill occurred because a tanker collided with a rig. The weakened rig was closed, and it collapsed upon impact, spewing oil into the Persian Gulf off the coast of Iran. The Nowruz Oil Field was located in an Iraq/Iran combat zone during wartime, which prevented the leak from being capped quickly. Oil spilled out of the rig at a rate of 63,000 gallons per day.

A month after the spill occurred, Iraqi forces attacked both the leaking rig and another nearby platform. Both caught fire and leaked a reported 30 million gallons of oil into the Persian Gulf by the time they were capped by Iranians in September.

13. The Torrey Canyon Oil Spill

The Torrey Canyon was one of the first big supertankers. Although the ship was originally built to carry 60,000 tons, it was enlarged to a 120,000-ton capacity, and that’s the amount the ship was carrying when it hit a reef off the coast of Cornwall.

The spill, called "the world's first major supertanker disaster," created an oil slick measuring 270 square miles, contaminating 180 miles of coastland. Tens of thousands of sea birds and enormous numbers of aquatic animals were killed before the spill was finally contained.

Toxic solvent-based cleaning agents were used by Royal Navy vessels to try to disperse the oil, but that didn't work very well and instead caused a great deal of environmental damage. It was then decided to set fire to the ocean and burn away the oil by dropping bombs.

14. Exxon Valdez Oil Spill

When the Exxon Valdez supertanker hit a reef off the Alaskan coast, 11 of its cargo tanks ruptured, dumping 11 million gallons of crude into Prince William Sound. The spill could have been much worse, considering the Valdez was carrying 53 million gallons; still, though, it wreaked havoc on the ecosystem.

Responders found carcasses of more than 35,000 birds and 1,000 sea otters, which was considered to be a fraction of the animal death toll because carcasses typically sink to the seabed. It’s estimated that 250,000 seabirds, 2,800 sea otters, 300 harbor seals, 250 bald eagles, and up to 22 killer whales died along with billions of salmon and herring eggs.

The Exxon Valdez oil spill was so damaging it prompted the Oil Pollution Act, aimed to increase federal oversight of oil extraction and hold companies financially accountable for spill events. The repaired Exxon Valdez was renamed the SeaRiver Mediterranean, and, although it is banned from Alaskan waters, the tanker still carries oil around the world. Meanwhile, oil from the spill remains a few inches below the surface on many of Alaska’s beaches.