Canadian mining company Nautilus Minerals Inc. (Nautilus) is set to embark on the unprecedented extraction of metals from the sea floor of the Bismarck Sean in Papua New Guinea through the project known as Solwara 1. This is the world's first commercial deep sea mining (DSM) operation. There is a high level of uncertainty about the rishks posed by deep sea mining to marine environments and to communities. This paper provides an overview of major impacts and critically assesses the adequacy of the data, assumptions and predictions found in Nautilus's 2008 Environmental Impact Statement.