Natural freshwater wetlands are the most vulnerable, of the key biological sites in arid landscapes of Saudi Arabia including ponds, streams and springs, as well as artificial wetlands such as reservoirs and effluent streams outside urban areas and agricultural developments. They attract and support a diverse assemblage of plants and animals and are important centers of endemism
Mangrove are widely scattered along the Red Sea and Gulf coasts. There are two species: Avicennia marina is the most common in both coasts while Rhizophore mucronata is found in only eleven sites in the Red Sea coast.
Broad inter-Tidal flats and sandy /rocky beaches are important for turtle nesting, fishing and recreational activities. Sub-Tidal habitats are of special important because they generate much of the energy in the coastal ecosystems.
Sand and Mud Flats are widely distributed, especially in the Gulf covering about 95% of the sub-tidal zone. Algae and invertebrates, account for the greates biomass in these large areas of relatively low productivity. Shrimp harvests are an important economic activity.