Earth’s ocean floor remains the least-charted giant landscape on the planet

Less than 30% of the world’s ocean floor is mapped to modern standards, while Mars and the Moon have globally detailed maps created with laser altimetry. Seawater absorbs measurement signals, so ship-based sonar remains the primary method for deep-sea mapping, leaving most of Earth’s largest landscape uncharted. The Seabed 2030 project and SWOT-derived data are gradually expanding coverage, but about 258 million square kilometres still lie outside the 28.7% currently charted, and progress depends on continued surveys and new data sources.