The dramatic reduction of sea ice in the Arctic Ocean will increase human activities in the coming years. This will be driven by increased demand for energy and the marine resources of a more accessable Arctic Ocean to ships. Oil and gas exploration, fisheries, mineral extraction, marine transportation, research and development, tourism and search and rescue will increase the pressure on the vulnerable Arctic environment. Synoptic in-situ year-round observational technologies are needed to monitor and forecast changes in the Arctic atmosphere-ice-ocean system at daily, seasonal, annual and decadal scales to inform and enable sustainable development and enforcement of international Arctic agreements and treaties while protecting this critical environment. The OceanObs’09 Conference Summary (Fischer et al., 2010) identifies active and passive ocean acoustics as a proven technology for in-situ ocean observing. This paper, building on earlier consensuses (Sagen et al. 2010; Dushaw et al. 2010), discusses multipurpose acoustic networks including subsea cable components in the Arctic. These networks provide communication, power, underwater and under-ice navigation, passive monitoring of ambient sound (ice, seismic, biologic and anthropogenic), and acoustic remote sensing (tomography and thermometry) supporting and complementing data collection from platforms, moorings and vehicles. This paper supports the development and implemention of regional to basin-wide acoustic networks as an integral component of a multi-disciplinary in-situ Arctic Ocean observatory.