Map of the Week – Mean underwater depth
Happy New Year! Have you ever wondered how deep the ocean is? Did you know that the estimate average depth of the ocean is 3,682 metres? This was calculated, using satellite measurements, by scientists from the National Oceanic and Atmospheric Administration (NOAA) and the Woods Hole Oceanographic Institution.  The is the deepest known location on Earth. It is located to the east of the Mariana Islands in the Pacific Ocean. The Mariana Trench’s length is more than 2,550 kilometers and it is 69 kilometers wide. One point in the Mariana Trench is recognized as the deepest point on Earth at 11,034 m. It is known as the Challenger Deep. 
Bathymetry is the measurement of the depth of water in the ocean, rivers, or lakes. In ancient times, scientists would conduct bathymetric measurements by throwing a heavy rope over the side of a ship and recording the length of rope it took to reach the seafloor. Today, echo sounders are used to make bathymetric measurements. An echo sounder sends out a sound pulse from a ship’s hull, or bottom, to the ocean floor. The sound wave bounces back to the ship. The time it takes for the pulse to leave and return to the ship determines the topography of the seafloor. The longer it takes, the deeper the water. 
Wish to know more?
- Learn about the five - the sunlight zone (epipelagic), the twilight zone (mesopelagic), the midnight zone (bathypelagic), the abyssal zone (abyssopelagic) and the hadal zone (trenches) with the Woods Hole Oceanographic Institution!
- Dive into the Map of the Week and find out what the mean underwater depth is at different locations!
- Interested in research vessels and underwater robots? Discover the Eurofleets+ Ocean Classroom Portal">!
The data in the map are provided by EMODnet.