Before revision: The region was initially discovered by American researchers during World War II in 1942 during anti-submarine research with sonar.Sonar at the time could not penetrate below this depth due to the large number of creatures obstructing sound waves.It is uncommon to detect deep scattering layers below 1000m.Until recently, sonar has been the predominant method for studying the mesopelagic.
After revision: The region was initially discovered by American researchers during