 The harbour is an expansive, almost landlocked, shallow bay of relatively uniform depth ranging from , which provides safe anchorage from the Roaring Forties that buffet the western and southern coasts of Tasmania.The harbour is connected by the narrow -long Bathurst Channel to Port Davey, and then water flows into the Southern Ocean.Like most estuarine systems in southwest Tasmania, the water is stained a deep red-brown due to tannin leached from buttongrass and adjacent heathland.