The Heuningnes Estuary, also known locally as De Mond, is a significant tidal estuary located in the Overberg District Municipality of South Africa, southwest of the village of Struisbaai near Cape Agulhas. It is a designated Ramsar site, recognized for its international importance as a wetland, and forms part of the De Mond Nature Reserve. This system is a non-perennial river estuary, meaning its connection to the sea at the mouth can be closed by a sandbar, creating a dynamic brackish environment. The estuary encompasses wetlands, estuarine lake characteristics, and provides critical habitat for a variety of bird and fish species, making it a valued conservation area and a destination for anglers seeking inshore saltwater fishing.