Irwin Inlet, also respectfully known by its Aboriginal dual name Quarram, is a wave-dominated estuary in the Shire of Denmark, Western Australia. This shallow, 13 to 14 square kilometre inlet is fed by the Kent (Gnowerumbup) and Bow (Waalitchup) rivers and discharges into the Southern Ocean at Foul Bay, bisecting Peaceful Bay (Kwallup) beach. A dynamic sandbar at the ocean entrance is often breached during winter, connecting the brackish inlet to the sea. The water body is characterized by its very shallow depth, mostly less than 2 metres, and supports extensive seagrass meadows. It is slowly infilling with sediment but remains a productive commercial and recreational fishery. The inlet is situated approximately 20 kilometres east of Walpole and 30 kilometres west of Denmark, with the South Coast Highway running about 3 kilometres to the north.