FTV February 19

Our time in Miami was great! Some of us went to one of the largest boat shows in the world. Many cadets spent a day on the famous South Beach working on their tans one last time before returning to cold Buzzards Bay.

As a big boat fan I choose to go to the boat show. The boats there were stunning and I now know my dream boat. As we leave the coast of Florida, we begin our journey up the Atlantic coast to our home in Buzzards Bay.

From the ship we see the only miles and miles of water, but often wonder what is at the bottom of all that water. What does the ocean bottom actually look like? What would we see if we could empty all of the water out of the ocean? How do scientists use technology to see the ocean floor? 

Science Wednesday:

Today's scientists who study the ocean (called oceanographers) have overcome many of the challenges of studying deep by using sophisticated tools. They can send manned submersibles and sampling devices to view the ocean depths, taking photographs and samples of animal life and sediment to bring back to the surface for further study. Even space technology enters the picture. Satellite photos taken of the ocean provide a wide range of information, including water temperature and depth, seafloor topography, and the plankton populations. Using sonar and satellite data, scientists have been able to generate a new map of the ocean floor, thirty times more accurate than the best previous map. This map shows the ruggedness of the Mid-Ocean Ridge as it bisects the Atlantic Ocean. This contrasts to the relatively flat Pacific Ocean floor, its vast expanse broken up by more than a thousand newly discovered underwater volcanoes stretching from Hawaii to the Aleutians.

Most of what scientists know about the ocean floor does not come from direct observation, but from the use of technology. Sonar, which stands for “sound, navigation and ranging,” is a technique that uses sound and echolocation to detect and locate objects submerged in water. In other words, sound waves are transmitted and then reflected in order to find a particular distance. Try this activity to Map the Ocean floor. 

The ocean floor has been mapped by scientists despite the fact that it is under water. Until recently, the depth of coastal waters, rivers, and lakes was measured by a weighted and marked line. Now depth sounders and sonar accomplish the same task more quickly and efficiently. In the past, people lowered weighted marked ropes into rivers, lakes and coastal waters to test depths. Today, sonar is used to determine bottom measurements. Sonar sends impulses of sound downward and measurements of depth are determined by the length of time it takes the sound impulse to travel to the water body bottom and bounce back again.
Watch this video about Sonar Technology, and then try this activity.
Scientists studying the seafloor often use bathymetric maps like the one below. These maps use color to indicate water depth. On most bathymetric images of the ocean, colors on the “warm” end of the spectrum – red, orange, and yellow - represent shallower water. As the water deepens, the colors shift through green, blue, and finally into violet. Dry land is usually shown in white. Learn more here

Try this hand’s on activity to simulate the pre-sonar method of mapping underwater terrain.