What tools do hydrographers use?

A multi-panel image showing ocean mapping and survey technology. The top panel displays a colorful bathymetric map. Below, a small yellow uncrewed surface vessel moves across the water. The third panel shows a high-resolution 3D map of the seafloor. The bottom panel features a person in a hard hat deploying a yellow torpedo-shaped autonomous underwater vehicle from a boat. — A group of four images from the top: an image of the Visual Lab at the Center for Coastal and Ocean Mapping/NOAA-UNH Joint Hydrographic Center; an uncrewed surface vessel during survey operations; a digital terrain map of the entrance to Portsmouth Harbor, New Hampshire; an image of an autonomous underwater vehicle being deployed. Credit: NOAA; University of New Hampshire.

Have you ever wondered how hydrographers are able to create such detailed and accurate nautical charts since the seafloor can’t be easily seen beneath the waves? Mapping the seafloor is very different from mapping Earth’s topography — or the physical features on land. While the location, shape, and size of structures on land can be determined using satellites, drones, or even our own eyes, the characteristics of the seafloor are hidden underwater, making them more difficult to measure and describe.

To solve this challenge, hydrographers rely on a range of impressive tools. These tools help measure water depth, can determine the location of objects on the seafloor, and gather vital information that is used to help keep ships safe as they travel.

This section explores some of the key tools that hydrographers use. Visit the pages in this section to learn more.

Tools of the trade and hydrographic ships - Explore the equipment hydrographers use in the field, as well as the specially designed ships they use to support their work.
Sonar - Discover how hydrographers use sound waves to “see” beneath the water, creating detailed maps of the seafloor.