Answer:
The marine tragedy being referred to is the sinking of the RMS Titanic, which hit an iceberg on its maiden voyage and sank on April 15, 1912.
The Labrador Current flows southward along the coast of Newfoundland and Labrador, bringing with it icebergs that have calved off the Greenland ice sheet. The Titanic was sailing through this region when it struck an iceberg that had drifted into its path, causing extensive damage to the ship's hull and leading to its sinking.
The tragedy resulted in the loss of more than 1,500 lives and is considered one of the deadliest peacetime maritime disasters in history.