Introduced by conference chairman Dick G. Simons, no less than four keynote speakers made their appearance. Dr Steve Ramberg of the NATO Undersea Research Centre spoke about the inseparable futures of undersea acoustics and marine life, while Prof. Andrea Caiti of the University of Pisa addressed the comprehensive EU project SITAR on Seafloor Imaging and Toxicity: Assessment of Risk caused by buried waste. Rear Admiral Van Koningsbrugge of the Royal Netherlands Navy and Dr Alan Edwards of the European Commission addressed military aspects and EC framework programmes of relevance to underwater acoustics, respectively.

Scientific Programme
Four parallel sessions were required to accommodate two hundred contributed papers and twenty poster presentations, and the overall level was generally considered high. Advances in both theoretical and practical matters associated with underwater acoustics passed in review. Significant sessions on seafloor mapping, geo-acoustic characterisation of fine-grained sediments and seabed interactions evidence considerable activity in the field of acoustic seafloor characterisation.
In another field, one of the observed trends is an increasing concern regarding the wellbeing of marine mammals. A dedicated session on sonar and the hearing of whales and dolphins revealed a better understanding of the influence of underwater sound on marine mammals and proposed impact mitigation tactics.
In underwater communications there is growing awareness that robust acoustic data transmission systems require some kind of diversity. For instance, the use of hydrophone antennas (as opposed to a single receiver hydrophone) is becoming more and more prevalent in both research and practical applications. In synthetic aperture sonar one of the observed trends concerns increased efforts towards the detection of buried objects. The diversity of the papers was high and the ECUA 2004 covered many more research areas than the few mentioned here.

Social Programme
To refresh the minds of scientist and exhibitor alike there was an icebreaker party, a warm reception at the Delft town hall, a dinner on a sailing paddle steamer and a sightseeing tour through The Hague. Indeed, all in all the ECUA 2004 was a nicely balanced event.