In order to describe an aquatic ecosystem scientists require a variety of information. Some of this information can be obtained using underwater acoustics. As examples acoustics is often used to provide information about biomass densities, biological species compositions, size distributions, behavior in space and time, and links to other environmental information such as habitats. Examples of underwater acoustic instrumentation used by scientists to obtain such information are scientific multi frequency split beam echo sounders, multi beam echo sounders, omni directional sonars, 3D matrix sonars, and various types of trawl gear instrumentation. Data are often obtained from fixed installations on board dedicated research vessels, but are sometimes also obtained from various kinds of moored installations, acoustic landers, remote buoys, autonomous underwater vehicles (AUV’s), and commercial fishery vessels. In this paper a variety of underwater acoustic technologies are presented to serve as input for the discussion of what kind of underwater acoustic instrumentation is needed for both research vessels, potentially commercial fishing vessels, and other types of installations in order to obtain improved information about the marine ecosystem in the Antarctic.