In 1997, a mysterious sound echoed across the Pacific. Years later, scientists traced the 'Bloop' to Antarctica

• The deep ocean has a way of turning ordinary events into unanswered questions.
• Far below the waves, sounds travel through water in ways that can make distant sources appear much closer or far stranger than they really are.
• In 1997, a powerful low-frequency noise recorded across the Pacific Ocean created one of the most unusual acoustic mysteries in modern marine science.