Abstract: A low cost sonobuoy is constructed of plastic pipe and fittings. A simple design is used comprising a section of plastic pipe and two end caps. One end cap is tapered and adapted for having an antenna mounted thereon. The other end cap has a recess for storing a hydrophone, cable and plastic streamers. The hydrophone and cable are held in place by water soluble tape. The sonobuoy may be launched from aircraft and thus the plastic streamers trail from the second end cap to provide in-air stability. The sonobuoy is designed to be self-righting and self-scuttling.