Why is it hard to explore the mariana trench ?

The deepest part of the trench, Challenger Deep, lies seven miles below the ocean surface. ... When one tectonic plate dives under another, trenches are formed. The sheer depth of Mariana trench makes it hard to explore. Sunlight does not reach that far down, shrouding it in permanent darkness.nation:

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.