It is mined for minerals (salt, sand, gravel, and some manganese, copper, nickel, iron, and cobaltcan be found in the deep sea) and drilled for crude oil. The ocean plays a critical role in removing carbon from the atmosphere and providing oxygen.
http://marinebio.org/oceans/ocean-resources/
<span>A: Some energy will be used to do work and some will be lost as heat.</span>
