In 1980 Texaco was doing exploratory drilling for oil in Lake Peigneur, a shallow man-made lake near New Iberia, LA. Although many of the facts from that day are lost, what we do know is that someone miscalculated and drilled right through the lake and into a salt mine below.
It’s generally accepted that the drill punctured the roof of the third level of the mine. This created an opening in the bottom of the lake, similar to removing the drain plug from a bathtub. The lake then drained into the hole, expanding the size of that hole as the soil and salt were washed into the mine by the rushing water, filling the enormous caverns left by the removal of salt over the years.
The resultant whirlpool sucked in the drilling platform, eleven barges, many trees and some of the surrounding terrain. Local media reports at the time stated that at least one fisherman had to abandon his small boat in the mud and walk back to shore, as his boat was now sitting on the lake bed, with him still sitting in it.
So much water drained into those caverns that the flow of the Delcambre canal that usually empties the lake into Vermilion Bay was reversed, making the canal a temporary inlet. This backflow created, for a few days, the tallest waterfall ever in the state of Louisiana, at 150 feet (50 m), as the lake refilled with salt water from the Delcambre Canal and Vermilion Bay.
The drilling company, Texaco and Wilson Brothers paid $32 million (USD) to Diamond Crystal and $12.8 million to nearby Live Oak Gardens in out-of-court settlements to compensate for the damage caused.
Here now is the History Channel footage of the ordeal.
You can also read a slightly more detailed account here.