Abstract: An apparatus for supporting a large volumetric array of acoustic sensors in water is packaged in a standard configuration sonobuoy envelope and utilizes conventional sonobuoy deployment components. A housing within the envelope contains a plurality of tubular extendable members stored on drums and extendable to form array support booms upon deployment of the apparatus. A plurality of releasable array modules are releasably attached to the housing, each module containing an array cable and a plurality of acoustic sensors secured to and along the cable. As the apparatus enters and descends through the water, the tubular members extend to form array support booms. The array modules are synchronously released to the extension of the tubular members and as the modules descend, the array cables and acoustic sensors deploy, the array cables forming catenaries between points on array support boom pairs or between the housing and points on the various booms.