Stretches of fine sands continuing at greater depth the biocenosis of fine sands at high level (III.2.1); the sediment is usually of homogeneous granulometry and terrigenous origin. The biocenosis begins at around 2-2.5 metres and may reach a depth of 25 metres; sometimes it occupies vast areas along the coasts or in wide bays. Locally, the biocenosis of well sorted fine sands tolerates a slight lack of saltiness in the water near estuaries and surrounding some Mediterranean ponds. It thus presents a certain impoverishment, offset by the presence of some euryhaline species. When the wave action is too strong, the biocenosis can also be impoverished. Locally, the Cymodocea nodosa phanerogam can colonise certain areas, where it will constitute a local facies with epiflora. The fairly localized presence of some species (Caulerpa prolifera, Halophila stipulacea...) also determines the forming of local facies.