How much of the ocean has been explored?

Despite covering 71% of Earth's surface and containing 97% of all water, only about 20% of the global ocean floor has been mapped using modern high-resolution sonar (as of 2023, per the Seabed 2030 project). Direct human or robotic exploration has covered an even smaller fraction — perhaps 5%. We have better maps of the Moon, Mars, and Venus than of our own ocean floor. The average ocean depth is 3,688 meters, and the deepest point (Challenger Deep) reaches 11,034 meters. The ocean contains an estimated 1–2 million undiscovered species. In recent years, each deep-sea expedition typically discovers dozens of new species. The Seabed 2030 initiative aims to map 100% of the ocean floor by 2030 using a combination of ships, autonomous underwater vehicles, and satellite-derived bathymetry.