Understanding Sonar Mapping of the Ocean Floor

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Author: Angela Pike

Grade Level: 1st - 5th; Type: Earth Science


To demonstrate sonar mapping of the ocean floor. 

Research Questions

  • What types of land formations can be found on the ocean floor?
  • How does sonar mapping measure ocean depth?
  • How does sonar mapping provide information about the ocean floor?

Despite what early explorers thought, the world is definitely not flat! This includes land masses and the ocean floor. Just as there are mountains, valleys, and plains on dry land, the ocean floor is comprised of long mountain chains, deep trenches, and flat plains. Topographic maps are used to provide information about different land elevations. Measuring the depth of the ocean to the ocean floor can be done through sonar mapping. Sonar mapping measures how long it takes sound waves to travel through the water to the ocean floor and back to the surface. In this investigation, a high-bouncing ball will be used to demonstrate how sound waves measure the depth to the ocean floor. 


  • High-bouncing ball
  • Stopwatch

Experimental Procedure

  1. Have a parent or friend use a stop watch to help you with this experiment. Drop the high-bouncing ball onto a hard, flat surface. Have your partner time from when the ball leaves your hand until it returns to your hand. Record the time on a data chart. (See sample below.)

Drop Location


Location 1-Sitting in a chair


Location 2-Standing up


Location 3-Standing on a chair

  1.  Repeat this procedure at different heights. For example, sitting on a chair, standing up, and standing on a chair. Record the time for each location.
  2. Upon completing this activity from 3-4 locations, use your data to draw a picture of what you think the ocean floor might look like. 

Terms/Concepts:  Land formations of the ocean floor (Ex: plains, trenches, ridges, mountains); Sonar


    2. (Good picture of sonar mapping image)
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