In 1997, the National Oceanic and Atmospheric Administration (NOAA) recorded a perplexing underwater sound known as "Bloop." This ultra-low-frequency noise was exceptionally loud, reaching hydrophones across the Pacific Ocean, leading to various speculations about its origin.
Initially, some theorized it could be from a massive, undiscovered sea creature. However, by 2006, NOAA scientists proposed that the "Bloop" was likely caused by a large icequake, where massive icebergs crack or collapse into the ocean. This explanation was reaffirmed in 2012, aligning the sound with glacial movements and iceberg calving, which are becoming more frequent due to global warming, as reported in 2025.
Icequakes are common near Antarctica and produce sounds similar to biological noises. In January 2025, such icequakes were even heard across Central Missouri, demonstrating the widespread nature of these events. The cracking and breaking of ice shelves continue to be a dominant source of natural sound in the Southern Ocean in 2025.