Southwest Pass is one of the channels at the mouth of the Mississippi River.^[1] It empties into the Gulf of Mexico at the southwesternmost tip of the Mississippi River Delta. It lies in Plaquemines Parish in southeastern Louisiana in the United States.^[2] It has been the main shipping channel in the Mississippi River Delta since 1853.

Southwest Pass should not confused with a strait in Vermilion Parish, Louisiana, also known as Southwest Pass.