The morphological characteristics of a coastal reef that is observed along the Ammoudara beach (6 km to the west of the city of Heraklion, Crete) are investigated in relation to the sedimentology and modern evolution of the adjacent beach zone. The reef has a length close to 4 km, a mean width close to 35m and is located at a distance of 60 m from the shoreline at an average water depth of 2.6m, while the seaward water depth exceeds 3m. Its height above the seafloor, exceeds 80 cm, reaching in places less than 0.5 m from the sea surface. It has two layers; the lower one which consists of fine grained (sandy) material and is approximately 40 cm thick and the upper layer, around 30 cm thick, consisting of relatively coarse,grained material (gravel and sand). Moreover, on the surface of the upper layer, runnels are observed, whilst distinguished cross bedding, similar to that observed in aeolian deposits, exists within the bottom layer. The reef is not present in front of the active mouths of the rivers Gazanos and Xiropotamos which debouch in the coastal area of Ammoudara. The western end of this submerged reef is attached to the beach face, exhibiting the characteristics of a typical beach,rock formation. On the basis of the above, it is concluded that the reef under investigation it is a submerged beach rock which indicates the position of a former coastline that is now submerged due to a relative sea level rise of approximately 0,5m.