We have a more accurate map of the surface of Mars than we do for Earth’s ocean floor. Right now, researchers have a blurry, indirect picture of the seabed from satellite imaging, some sonar data and samples collected from ships.
Yes, but: There's an avalanche of data about the chemical, physical and biological properties of the ocean, and scientists are beginning to use machine learning to tie that data to limited scientific records in hopes of piecing together a better picture.
Why it matters: The ocean is the planet's largest carbon sink thanks to processes that critically depend on the seafloor, and sediment layers hold a record of the ocean's chemical and climatic history. Understanding the ocean floor is key for climate forecasts and predicting geohazards like tsunamis as well as for efforts to mine the seas for methane and minerals.