Armour layer assembly (117, 201, 203) for a breakwater (100, 200), comprising: - a plurality of horizontal rows (13, 14, 15) of armour elements, and - a horizontal row of crest elements; wherein each armour element comprises a central part, two wings (3, 4) extending from the central part in opposing directions along a length direction of the breakwater (100, 200), a tail extending from the central part in a backward direction towards the breakwater (100, 200) and transverse to the length direction of the breakwater (100, 200), and a nose extending from the central part in a forward direction opposite to the backward direction; wherein the wings (3, 4) of the armour elements of each said horizontal row are mutually aligned; wherein the noses of the armour elements of an above said horizontal row of armour elements are supported on the armour elements of a below said horizontal row of armour elements; wherein each crest element comprises: - a central part having an upper side, a lower side, a backside, a front side, a left side, and a right side, - two wings (103, 104) extending from the right side and left side, respectively, of the central part in opposing directions along, when placed on a breakwater (100, 200), the length direction of the breakwater (100, 200), and - a nose extending from the front side of the central part in the forward direction transverse to the length direction of the breakwater (100, 200); wherein the wings (103, 104) of the crest elements of the horizontal row of crest elements are mutually aligned; wherein the wings (103, 104) of the crest elements have a backside which is a vertically oriented, back face; and wherein the horizontal row of crest elements is placed above an upper said horizontal row of the plurality of horizontal rows (13, 14, 15) of armour elements with the noses of the crest elements of the horizontal row of crest elements supported on top of the armour elements of the upper horizontal row of armour elements; characterised, in that the backside of the central part of the crest elements consists of a vertically oriented, back face facing in the backward direction; and in that the vertically oriented, back face of the wings (103, 104) of each said crest element is flush with the back face of the central part of the respective crest element. - a plurality of horizontal rows (13, 14, 15) of armour elements, and - a horizontal row of crest elements; wherein each armour element comprises a central part, two wings (3, 4) extending from the central part in opposing directions along a length direction of the breakwater (100, 200), a tail extending from the central part in a backward direction towards the breakwater (100, 200) and transverse to the length direction of the breakwater (100, 200), and a nose extending from the central part in a forward direction opposite to the backward direction; wherein the wings (3, 4) of the armour elements of each said horizontal row are mutually aligned; wherein the noses of the armour elements of an above said horizontal row of armour elements are supported on the armour elements of a below said horizontal row of armour elements; wherein each crest element comprises: - a central part having an upper side, a lower side, a backside, a front side, a left side, and a right side, - two wings (103, 104) extending from the right side and left side, respectively, of the central part in opposing directions along, when placed on a breakwater (100, 200), the length direction of the breakwater (100, 200), and - a nose extending from the front side of the central part in the forward direction transverse to the length direction of the breakwater (100, 200); - a central part having an upper side, a lower side, a backside, a front side, a left side, and a right side, - two wings (103, 104) extending from the right side and left side, respectively, of the central part in opposing directions along, when placed on a breakwater (100, 200), the length direction of the breakwater (100, 200), and - a nose extending from the front side of the central part in the forward direction transverse to the length direction of the breakwater (100, 200); wherein the wings (103, 104) of the crest elements of the horizontal row of crest elements are mutually aligned; wherein the wings (103, 104) of the crest elements have a backside which is a vertically oriented, back face; and wherein the horizontal row of crest elements is placed above an upper said horizontal row of the plurality of horizontal rows (13, 14, 15) of armour elements with the noses of the crest elements of the horizontal row of crest elements supported on top of the armour elements of the upper horizontal row of armour elements; characterised, in that the backside of the central part of the crest elements consists of a vertically oriented, back face facing in the backward direction; and in that the vertically oriented, back face of the wings (103, 104) of each said crest element is flush with the back face of the central part of the respective crest element.