Answer:
The <em>deep ocean</em> contains 90% of Earth's seawater!
Explanation: The deep ocean is the bottom part of the ocean, while the surface ocean is the uppermost part. These two zones are separated by the <em>thermocline</em>, which is a collection of layers of water where temperatures decrease rapidly the deeper you go. Once you reach the deep ocean (at approximately 1,800 meters and more), temperatures are extremely low!
Dormant volcanoes are know as sleeping volcanoes... :)
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I hope this helps and have a wonderful day filled with joy!!