This was published in 2011 but remains a nice summary of the major issues concerning exploitation and protection of the deep ocean; an area we still know little about.
http://www.theguardian.com/science/blog/2011/aug/03/protected-areas-deep-sea-environment
I’m not sure if the area dimension given in the third paragraph is correct? 360 million km2 for the deep ocean seems very small? Have to check this 🙂