According to NOAA, as of 2018, 90% of the ocean has been unmapped by sonar. However, NASA published an animation showing the entire seafloor in 2008 and remade it this year. How do you explain this discrepancy?
https://oceanservice.noaa.gov/facts/exploration.html
https://www.forbes.com/sites/trevornace/2020/02/03/nasa-reveals-what-earth-would-look-like-if-the-oceans-dried-up/#50fb33a74094