The remote sensing of oceans from space has developed rapidly since 1978 when the first dedicated ocean viewing sensors were launched. In 1991 the first European Space Agency remote sensing satellite carried sensors primarily for the ocean, heralding the widespread use of satellite data by oceanographers. In the mid 1990s the US/French TOPEX-Poseidon mission revolutionised the performance of satellite altimetry and since 1997 NASAs SeaWiFS mission has delivered operational measurements of ocean colour. The new millennium has seen the launch of several very large remote sensing platforms and a number of smaller missions by ESA, NASA and NASDA, providing almost comprehensive worldwide measurements of sea surface waves and wind, temperature, colour, currents and other ocean properties. The increasing availability of so much satellite data has undoubtedly changed the way the science of oceanography has developed. The unique perspective provided by satellites has revealed previously undetected ocean phenomena, cast new light on old problems, and opened the way for new fields of oceanographic study. This is the basis of Ian Robinsons latest book Understanding the Ocean from Space which takes a wide look at the ways satellite data have been applied to the study of the ocean. Its particular theme is to point out the special contributions or new insights which only satellite data could have brought to various aspects of oceanography. Each chapter takes a particular topic in ocean science and shows the variety of ways in which the measurements made by Earth-orbiting sensors can be applied to it. The topics range from ocean waves, to ocean biology, spanning scales from ocean basins to estuaries. Some chapters are largely about applications to pure research whilst others show how satellite data can be used operationally for tasks such as pollution monitoring or oil spill detection. The final subject to be addressed is the emergence of 'operationaloceanography', in which satellite and in situ data are ingested into model-based ocean forecasting systems. During the next decade these will transform the way in which day-to-day information about the state of the sea is made available. For each oceanographic topic that is considered a brief outline is given of the remote sensing methods which are applicable, but most emphasis is given to discussing the new scientific insights or operational advantages which flow from using satellite data. Wherever possible these are illustrated with case studies and examples of ocean image data. This book is a natural companion to the authors recent Measuring the Oceans from Space in which the fundamental methods and principles of satellite oceanography are systematically explained. By use of frequent cross-references to the comprehensive information in that book about sensors and sensing techniques, Understanding the Ocean from Space is able to focus on oceanographic phenomena and processes instead of technical procedures and instrument details. This makes it an inviting text for introducing undergraduate and postgraduate students of oceanography and earth or environmental science to the applications of remote sensing. At the same time it offers the research oceanographer a well-matched complement to Measuring the Oceans from Space. Together the two books provide a wide ranging reference source on a subject of growing importance for practising oceanographic scientists.