A swallet is a sudden breach of water into a mine, often occurring when miners accidentally intersect a hidden subterranean stream, a flooded karst cavity, or old inundated workings. The term originally referred to natural sinkholes or water swallows in limestone districts, but miners adopted it to describe the catastrophic flooding events that threaten crews and equipment.
Heard on the job
We hit a swallet on the third level and had to abandon the heading before the pumps were overwhelmed.