Naval warfare and the threat it poses have been the greatest motivation for underwater acoustics, starting with World War I (WWI) and reaching remarkable levels of achievement during and after World War II (WWII). These efforts led to basic discoveries in oceanography and acoustic science and engineering, including sonar and geophysical exploration.
The history of underwater acoustics over the first half of the 20th century includes its initial development, followed by a myriad of accomplishments through two world wars. This is a very broad and voluminous topic, for which only highlights can be given in this brief sketch. The material covered is largely derived from three special sessions on the topic, chaired by the authors at the 169th meeting of the Acoustical Society of America (ASA) held in Pittsburgh, PA. . . .