Cambridge Gulf is a gulf on the north coast of Western Australia. Many rivers flow into the gulf including the Ord River, Pentecost River, Durack River, King River and the Forrest River, making the environment an estuarine one.
The gulf experiences two large tidal flows each day between 7 and 9 metres (23 and 30 ft).
The town of Wyndham, the area's principal port lies on its eastern bank at the lower part of the gulf and is approximately 100 kilometres (62 mi) by road west-north-west of Kununurra. Cambridge Gulf is a gulf within a gulf, being at the southern extremity of the Joseph Bonaparte Gulf, in the Timor Sea.
The entrance of the Gulf is defined by Cape Domett on the eastern shore, Lacrosse Island in the middle, and the Cape Dussejour on the western shore.
The conjunction between the gulf and the lower regions of the Ord River (the eastern arm), and the Durack and Pentecost Rivers (the western arm) are the main areas that have estuarine features
The western shore of the gulf is backed by high sandstone hills that are 30 metres (98 ft) to 250 metres (820 ft) in height and with fringing colonies of mangroves and mudflats when the tide is low. Dense mangrove stands fringe the marshy area on the eastern shore of the gulf. Adolphus Island splits the southern end of the sound with a navigatable channel being found on the western arm.
The traditional owners of the area are the Jeidji peoples.
On 17 September 1819 Philip Parker King on the survey cutter HMS Mermaid, who was mapping the entire north Australian coastline, had landed at Lacrosse Island, from where he noticed a "deep opening" to the south.