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, 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 15-20 percent of the ocean floor has been mapped with modern high-resolution technology.
Seafloor Mapping: The Foundation for Healthy Oceans and a Healthy Planet
Ocean Mapping: an Essential Part of Ocean Exploration - Discovering the Deep: Exploring Remote Pacific Marine Protected Areas
Introduction to Sonar and Multibeam Mapping
Mapping the Ocean Floor (pdf, 528 KB)