Early in the morning on November 21, 1980, twelve men decided to abandon their oil drilling rig on the suspicion that it was beginning to collapse beneath them. They had been probing for oil under the floor of Lake Peigneur when their drill suddenly seized up at about 1,230 feet below the muddy surface, and they were unable free it. In their attempts to work the drill loose, which is normally fairly easy at that shallow depth, the men heard a series of loud pops, just before the rig tilted precariously towards the water.
At the time, Lake Peigneur was an unremarkable body of water near New Iberia, Louisiana. Though the freshwater lake covered 1,300 acres of land, it was only eleven feet deep. A small island there was home to a beautiful botanical park, oil wells dotted the landscape, and far beneath the lake were miles of tunnels for the Diamond Crystal salt mine.
Concluding that something had gone terribly wrong, the men on the rig cut the attached barges loose, scrambled off the rig, and moved to the shore about 300 yards away. Shortly after they abandoned the $5 million Texaco drilling platform, the crew watched in amazement as the huge platform and derrick overturned, and disappeared into a lake that was supposed to be shallow. Soon the water around that position began to turn. It was slow at first, but it steadily accelerated until it became a fast-moving whirlpool a quarter of a mile in diameter, with its center directly over the drill site.
As the whirlpool was forming on the surface, Junius Gaddison, an electrician working in the salt mines below, heard a loud, strange noise coming down the corridor. Soon he discovered the sound's source, which was rushing downhill towards him: fuel drums banging together as they were carried along the shaft by a knee-deep stream of muddy water. He quickly called in the alarm, and the mine's lights were flashed three times to signal its immediate evacuation. Many of the 50 miners working that morning, most as deep as 1,500 feet below the surface, saw the evacuation signal and began to run for the 1,300 foot level, where they could catch an elevator to the surface. However, when they reached the third level, they were blocked by deep water.
Clearly, the salt dome which contained the mine had been penetrated by the drill crew on the lake. Texaco, who had ordered the oil probe, was aware of the salt mine's presence and had planned accordingly; but somewhere a miscalculation had been made, which placed the drill site directly above one of the salt mine's 80-foot-high, 50-foot-wide upper shafts. As the freshwater poured in through the original 14-inch-wide hole, it quickly dissolved the salt away, making the hole grow bigger by the second. The water pouring into the mine also dissolved the huge salt pillars which supported the ceilings, and the shafts began to collapse.
As most of the miners headed for the surface, a maintenance foreman named Randy LaSalle drove around to the remote areas of the mine which hadn't seen the evacuation signal, and warned the miners there to evacuate. The miners whose escape was slowed by water on the third level used mine carts and diesel powered vehicles to make their way up to the 1,300 foot level, where they each waited their turn to ride the slow, 8-person elevator to the surface as the mine below them filled with water. Although it seemed to take forever to get out, all 50 miners managed to escape with their lives.
Meanwhile, up on the surface, the tremendous sucking power of the whirlpool was causing violent destruction. It swallowed another nearby drilling platform whole, as well as a barge loading dock, 70 acres of soil from Jefferson Island, trucks, trees, structures, and a parking lot. The sucking force was so strong that it reversed the flow of a 12-mile-long canal which led out to the Gulf of Mexico, and dragged 11 barges from that canal into the swirling vortex, where they disappeared into the flooded mines below. It also overtook a manned tug on the canal, which struggled against the current for as long as possible before the crew had to leap off onto the canal bank and watch as the lake consumed their boat.
After three hours, the lake was drained of its 3.5 billion gallons of water. The water from the canal, now flowing in from the Gulf of Mexico, formed a 150-foot waterfall into the crater where the lake had been, filling it with salty ocean water. As the canal refilled the crater over the next two days, nine of the sunken barges popped back to the surface like corks, though the drilling rigs and tug were left entombed in the ruined salt mine.
Despite the enormous destruction of property, no human life was lost in this disaster, nor were there any serious injuries. Within two days, what had previously been an eleven-foot-deep freshwater body was replaced with a 1,300-foot-deep saltwater lake. The lake's biology was changed drastically, and it became home to many species of plants and fish which had not been there previously.
Of course numerous lawsuits were filed, and they were subsequently settled out-of-court for many millions of dollars. The owners of the Crystal Diamond salt mine received a combined $45 million in damages from Texaco and the oil drilling company, and got out of the salt mining business for good.
No official blame for the miscalculation was ever decided, because all of the evidence was sucked down the drain, but the story described here is the generally accepted theory of what caused this massive disaster.
Update 16 March 2013: Ron Davis wrote in with a little history about the drill rig in question.