The sperm whale produces the loudest biological sound known, with its echolocation clicks estimated to exceed 230 decibels underwater.
Sperm whales make powerful broadband clicks using air passed through structures in the nasal passages. A specialized organ called the spermaceti organ helps focus and shape the sound. The returning echoes allow the whale to locate prey and navigate in darkness.
These clicks are especially important during deep dives, when sperm whales hunt squid and fish far below the sunlit surface. Their enormous heads contain the largest brains of any living animal, although brain size alone does not explain their acoustic power.
Underwater decibels cannot be compared directly with airborne decibels because the reference pressures differ. That distinction is why a very high underwater figure should not be treated as an equivalent everyday loudness measurement on land.