This volume examines the deep sea ecosystem from a variety of perspectives. The initial chapters examine the deep-sea floor, the deep pelagic environment and the more specialised chemosynthetic environments of hydrothermal vents and cold seeps. These environments are examined from the perspective of the relationship of deep-sea animals to their physico-chemical environment. Later chapters examine the biogeography of the main deep oceans (Atlantic, Pacific and Indian) with particular attention to the downward flux of surface-derived organic matter and how this drives the processes within the deep-sea ecosystem. The peripheral deep seas including the polar seas and the marginal deep seas (inter alia the Mediterranean, Red, Caribbean and Okhotsk seas) are explored in the same context. The final chapters examine the processes occurring in the deep sea and include an analysis of why the deep sea has high species diversity, how the fauna respond to organic input and how species have adapted reproductive activity in the deep sea. The volume concludes with an analysis of the anthropogenic impact on the deep sea.