Acoustic imaging has existed for almost 100 years. It is the most popular imaging modality in earth science, biomedicine, and fisheries. In living organisms, sound fields interact with microstructures, creating typical acoustic responses. These so-called acoustic fingerprints enable the identification, characterisation, discrimination and quantification of, e.g., species, tissue types, and diseases. Under specific conditions, acoustic signals can be used to manipulate or even disrupt microstructures and to impact natural vocalisation in terrestrial and marine animals. Yet, despite our vast knowledge on the propagation of sound, little is understood about the interactions of sound with microstructures in biomaterials or how sound effects an animal response. The 1st workshop on micro-acoustics in marine and medical research brought together research professionals with particular expertise on this topic and with diverse backgrounds including agricultural engineering, cell biology, marine biology, electrical engineering, gastroenterology, and astrophysics. The workshop was organised by the University of Bergen and the Institute of Marine Research (IMR). It took place at the IMR and the research vessel G.O. Sars, located in Bergen, Norway, on the 7th and the 8th of December, 2011. The outcomes are presented in this book. Each chapter treats a marine or medical application of the evolving field that we dubbed micro-acoustics. To prevent confusion with surface-acoustic-waves research (microacoustics), we added a dash. Although the workshop had been initiated to exchange ideas and to define future perspectives, the most important finding was that marine and medical acoustics research communities can mutually benefit from close collaborations. We are grateful to Bergen universitetsfond for granting the financial support for organising the workshop and to the medical imaging research & development cluster MedViz for enabling the printing of this book. But most of all we thank you for opening this book to learn more about the exciting field of micro-acoustics in marine and medical research!