A modular structure for being at least partly submerged in a body of water, where the modular structure comprises a plurality of structure elements, where each structure element comprises polymers, where each structure element comprises at least one protruding part and at least one receiving part wherein the protruding parts of a structure element are arranged for mating connection with the receiving parts on another structure element, the direction of mating motion defining a longitudinal direction of the structure element; - the modular structure comprises strengthening elements (9, 10, 18) for providing structural integrity to the modular structure, where the strengthening elements (9, 10, 18) are enveloping and/or penetrating at least parts of at least two structure elements of the modular structure; - the structure elements are adapted to form longitudinal channels inside the at least one protruding part and at least one receiving part, where the channels communicate across two or more structure elements that are in a mated connection; - the modular structure forms at least one closed structure, where a number of structure elements that overlap partially or completely in the longitudinal direction are connected in a network that closes upon itself around a volume; and - where the structure elements and strengthening elements (9, 10, 18) are adapted to provide flexibility to the modular structure while maintaining its structural integrity by at least one of the following i) comprising material with inherent elasticity, and ii) being formed to allow relative movement between at least two structure elements; where the modular structure is characterized in that: - the structure elements have apertures adapted to form channels through the structure elements in at least one direction transverse to the longitudinal direction; - the channels are adapted to guiding elongated strengthening elements. - the modular structure comprises strengthening elements (9, 10, 18) for providing structural integrity to the modular structure, where the strengthening elements (9, 10, 18) are enveloping and/or penetrating at least parts of at least two structure elements of the modular structure; - the structure elements are adapted to form longitudinal channels inside the at least one protruding part and at least one receiving part, where the channels communicate across two or more structure elements that are in a mated connection; - the modular structure forms at least one closed structure, where a number of structure elements that overlap partially or completely in the longitudinal direction are connected in a network that closes upon itself around a volume; and - where the structure elements and strengthening elements (9, 10, 18) are adapted to provide flexibility to the modular structure while maintaining its structural integrity by at least one of the following i) comprising material with inherent elasticity, and ii) being formed to allow relative movement between at least two structure elements; - the structure elements have apertures adapted to form channels through the structure elements in at least one direction transverse to the longitudinal direction; - the channels are adapted to guiding elongated strengthening elements.