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Airgun array. This is used to carry out seismic surveys to learn about the geology of the underwater rocks. The airguns discharge high-pressure air into the sea, creating loud bangs. These create seismic waves in the underlying rock. The reflected sound is detected with hydrophones (underwater microphones) and analysed to find out about the structure of the rock below. The vessel is the British Antarctic Survey's Royal Research Ship James Clark Ross. Photographed in the East Scotia Sea in 1996. (KEYSTONE/SCIENCE PHOTO LIBRARY/BRITISH ANTARCTIC SURVEY)