What is the difference between a topographic map and a bathymetric map?
Topographic maps show elevation of landforms above sea level; bathymetric maps show depths of landforms below sea level.
High-resolution bathymetry mapping data collected by the multibeam sonars of NOAA Ship Okeanos Explorer revealed complex topographic features around Saba Valley, near Puerto Rico. Image courtesy of the NOAA Office of Ocean Exploration and Research, Exploring Deep-sea Habitats off Puerto Rico and the U.S. Virgin Islands. Download image (jpg, 63 KB).
A map is a flat model of all or part of Earth’s surface drawn to a specific scale. The better maps communicate information, the more effective they are as a real-world model.
Topographic maps show elevation of landforms above sea level. Bathymetric maps show depths of landforms below sea level. Topographic elevations and bathymetric depths are often shown on maps with contour lines. A contour line represents a corresponding imaginary line on the surface of the land or bottom of the ocean that has the same elevation or depth along its entire length.
Since the ocean floor is not visible to us, it can be difficult to map. Over time, the technologies to map the seafloor have evolved to be faster and provide higher-resolution data. But even with today's technology and despite the fact that the ocean covers more than 70 percent of our planet’s surface, only 26.1 percent of the ocean floor has been mapped with modern high-resolution technology as of June 2024.