Elster Creek is a very compromised, polluted urban waterway. Almost all of the original vegetation communities on the sandbelt surrounding the waterway have vanished with suburban development. Some flora remnants still remain giving testimony to the splendour of the natural vegetation that once flourished here.  Elster Creek catchment is about 40 square kilometres in area. Most of this waterway is concreted except for the section in the Elsternwick Park Nature Reserve where I am placing a hydrophone.The Elsternwick Nature Reserve is replacing a former golf course and the masterplan will return many plants to this area that are now locally extinct. The Reserve is being designed with habitat and wildlife in mind. Listening to the creek and recording the sounds of the macro invertebrates living there now allows us to hear the baseline health of the waterway as this restoration project begins. Sound brings us in tune with and helps us understand the local underwater biodiversity. We have been using sound as a tool for young people too, to think below the surface and understand how our behaviour around our waterways affects not just local health but the ocean as a whole. As it is one ocean - we are all connected through our waterways.