Disaster: Oil spills
Going since: Around 1966
Damage done: The Deepwater Horizon incident may have been the worst oil spill in U.S. history, but it pales in comparison to the ongoing catastrophe that has afflicted Nigeria's Niger River Delta over the last five decades. As many as 546 million gallons of oil are believed to have spilled since oil exploration began in this region -- the equivalent of an Exxon Valdez spill every year.
There are around 2,000 official spill sites in the region, some of them decades old.
Oil companies operating in the region blame thieves and sabotage for the majority of the spills, though local activists say aging equipment and lax safety are the cause of many of them. The number of severity of the spills may actually increase in coming years as the industry moves into more remote and difficult terrain in the delta.
It's not just the spilled oil that can be dangerous. Pipeline explosions, like in the one that killed more than 100 people outside Lagos in 2008, are increasingly frequent as well.