The Bureau of the Ad Hoc Working Group of the Whole has considered an advance, unedited version of the technical abstract for presentation to delegates attending the third session of the Preparatory Committee on an international legally binding instrument under the United Nations Convention on the Law of the Sea on the conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction. The full text of the first World Ocean Assessment, including the summary, is available from www.un.org/depts/los/rp. The patterns of marine biodiversity are shaped by variations in the depth and nature of the seabed, by variations in temperature, salinity, nutrients and currents of the water column, and by the latitudinal and seasonal variations in sunlight. The size and complexity of the ocean means that patterns in global biodiversity are largely unquantified and their natural drivers not fully understood. It also reveals likely future trends and indicates management options likely to be more sustainable. Uncertainties, however, remain and surprises will be encountered (chap.