Oyster Harbour is a permanently open estuary covering approximately 15.6 square kilometres near Albany in Western Australia. It is fed by the King River and the Kalgan River, both of which discharge into the harbour before it connects to King George Sound via a narrow entrance channel at Emu Point. The harbour is generally shallow along its eastern shore, with depths exceeding 5 metres near the western shore and the southern basin. The entrance channel between the sandy spit of Emu Point and the rocky eastern shore is scoured to over 10 metres deep.

The Albany Visitor Centre lists several paddling routes in and around the harbour. The Emu Point to Whaler's Cove paddle is described as a longer route requiring a vehicle shuffle, running parallel to Middleton Beach between Emu Point and Ellen Cove, with views of Mt Clarence, Mt Adelaide, and large ships anchored in King George Sound. Large rays and small fish are commonly visible in the shallows close to shore along this route.

There are two main boat launching sites within Oyster Harbour. The Emu Point facility is the primary access point, with a dredged channel providing access to the Emu Point Boat Pens. The Lower King facility is located along the western foreshore in a dredged basin; however, it has been noted as having a slippery and uneven ramp surface, limited parking, and no universal access provisions. Informal launch sites also exist at the entrances to the King and Kalgan Rivers. Speed restrictions apply within the harbour, with designated 3.5-knot and 8-knot zones marked on the boating guide. Courtesy moorings suitable for vessels up to 15 metres are available for public use, limited to 72 hours with a maximum of 4 hours unattended.

The harbour supports a significant population of waterbirds, including the Western Australian Pelican, making it of interest to paddlers who enjoy wildlife observation. At the northeastern end near the Kalgan River mouth, the Albany Fish Traps are a site of considerable cultural significance to the local Mineng people, constructed over 7,500 years ago. Boat cruises also operate on the harbour and venture up the Kalgan River, so paddlers should be aware of vessel traffic, particularly near the main channel and Emu Point.