The Bio-Duck
For 50 years, submarines in the Southern Ocean picked up a strange, repeating quack that no one could identify.
What was reported
From the 1960s, submarine crews in the Southern Ocean, including off Western Australia, heard a strange, rhythmic sound on their sonar: a series of short, low pulses that sounded like a duck quacking. They called it the 'bio-duck'.
It was heard again and again, often in winter and spring, and for decades scientists couldn't tell what made it. Some suspected an animal; others, a machine.
Explanations offered
In 2014, scientists attached recording tags to Antarctic minke whales and found that they make the bio-duck sound. The whales are hard to see and study, which is why the source stayed hidden for so long.
- When
- Heard since the 1960s; identified in 2014
- Where
- Southern Ocean, off Western Australia and Antarctica
- Witnesses
- Submarine crews and ocean scientists
- Status
- Explained
Famous cases are real, widely reported events. Each file sets out what witnesses said and the explanations that have been offered, without taking a side.