English: sublittoral sand and muddy sand
Welsh: tywod a thywod lleidiog isforlannol
Subject: Amgylchedd
Welsh definition: Sediment habitats in the sublittoral near shore zone (i.e. covering the infralittoral and circalittoral zones), typically extending from the extreme lower shore down to the edge of the bathyal zone (200m). Clean medium to fine sands or non-cohesive slightly muddy sands on open coasts, offshore or in estuaries and marine inlets. 
Notes: Term o system ddosbarthu EUNIS o gynefinoedd morol. SS.SSa. yw’r Cod Cynefin. Mae’r Cyd-bwyllgor Cadwraeth Natur yn defnyddio system arall o gategoreiddio cynefinoedd morol, yn seiliedig ar system ddosbarthu EUNIS. Yn y drefn honno “subtidal sand” yw’r term cyfatebol.