---
source: https://iinventedlight.com/library/notes/sonar-basics.md
title: "Sonar: how sound waves map the ocean"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "US government work, public domain; restated in our own words"
attribution: "Summary by iinventedlight (AI-assisted). Sources: NOAA, Sonar - NOAA Ocean Exploration, US government work, public domain; NOAA, What is sonar?, US government work, public domain."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-04
status: published
checked_on: 2026-11-04
as_of: 2026-11-04
confidence: medium
untested: "No observation or experiment was done; only the fetched government pages were read."
category: coverage-gaps
topic_area: "ocean science: exploration tools"
tags: ['noaa', 'sonar', 'ocean', 'mapping']
sources:
  - id: S1
    title: "Sonar - NOAA Ocean Exploration"
    publisher: NOAA
    url: https://oceanexplorer.noaa.gov/technology/sonar/sonar.html
    accessed: 2026-11-04
    license: "US government work, public domain"
  - id: S2
    title: "What is sonar?"
    publisher: NOAA
    url: https://oceanservice.noaa.gov/facts/sonar.html
    accessed: 2026-11-04
    license: "US government work, public domain"
---
# Sonar: how sound waves map the ocean

**Answer:** Sonar, short for Sound Navigation and Ranging, is a tool that uses sound waves to explore the ocean. It works well underwater because sound waves travel farther in the water than radar and light waves can.

## What NOAA uses it for

Scientists primarily use sonar to develop nautical charts, locate underwater hazards to navigation, search for and identify objects in the water column and on the seafloor such as shipwrecks, and map the seafloor itself.

## The hardware

The sonar system consists of physical sound sensors called transducers. Scientists may use a single transducer or a group of them, called a transducer array. An array can be attached to a remotely operated vehicle, an autonomous underwater vehicle, a ship, or a platform like a towfish or glider.

## Active sonar

There are two types of sonar: active and passive.

- Active sonar transducers emit an acoustic signal or pulse of sound into the water.
- If an object is in the path of the sound pulse, the sound bounces off the object and returns an "echo" to the transducer.
- If the transducer can receive signals, it measures the strength of the signal.
- By determining the time between the emission of the sound pulse and its reception, the transducer can determine the range and orientation of the object.

## Claims
- id: C1
  claim: Sonar uses sound waves to explore the ocean.
  source: S1
  evidence: "is a tool that uses sound waves to explore the ocean."
- id: C2
  claim: There are two types of sonar, active and passive.
  source: S1
  evidence: "There are two types of sonar—active and passive."
- id: C3
  claim: Sonar uses sound waves to see in the water.
  source: S2
  evidence: "Sonar uses sound waves to 'see' in the water."

## Sources
- [S1] Sonar - NOAA Ocean Exploration. NOAA. https://oceanexplorer.noaa.gov/technology/sonar/sonar.html . License: US government work, public domain. Accessed 2026-11-04.
- [S2] What is sonar?. NOAA. https://oceanservice.noaa.gov/facts/sonar.html . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).