How the Depth of the Ocean Floor is Determined

The depth of the ocean floor is no longer undetermined as oceanographers found a way to measure this previously immeasurable depth.  In the old days, the depth was measured using a piece of rope, which was marked off at 6-foot intervals. This was cumbersome and time-consuming, however, so oceanographers found other ways that are more reliable and convenient. Nowadays, the depth of the ocean floor is usually measured using these two methods: echo sounders and satellite altimeters.

Echo sounders

These are devices that could transmit sound to the ocean floor (10-30 kHz) and then receive the echo that bounces back from the ocean floor. The depth of the ocean is computed by multiplying the speed the sound travels with the time interval when the echo was received by the device.  When the result is divided by two, this would yield the depth of the ocean floor. By considering other factors like temperature and salinity of the body of water, the depth of the ocean can then be measured accurately. This is based on the fact that the speed of sound in water is 1,500 m per second. The device has improved throughout the years as new features, such as the multi-beam sensors, were added to facilitate measurement and calculations of the ocean’s depth. It is also now more handy and easier to manipulate.

Satellite altimeters

These are radars on satellites which profile the surface of the sea to be able to measure the sea floor. The shape of the sea surface reflects the shape of the sea floor. Sea mounts or volcanoes would have a water bulge on the surface. This may not be visible to the naked eye because of the decreased slope of the ocean surface. Gravity plays a crucial role in this process because it helps determine which part of the ocean has a mountain or not.  Due to gravity, the mountain would naturally attract more water causing the bumps or bulges on the sea surface. A good example of a satellite altimeter is Jason 2 altimeter, which has provided significant data about the depths of oceans around the globe.

Through these devices and the hard work of adventurous oceanographers, the Challenger Deep was discovered as the deepest part of the ocean. According to the National Oceanic and Atmospheric Administration (NOAA), the Challenger Deep is about 36,200 feet, or 11,030 meters.  With the ingenuity of enterprising people, the ocean floor is no longer an uncharted territory; it has been mapped and measured accurately.