Chemical self-assembly is the process by which ＇programmed＇ molecular subunits spontaneously form complex supramolecular frameworks(1,2). This approach has been applied to many model systems, in which hydrogen bonds(3,4), metal-ligand coordination(5) or other non-covalent interactions(6) typically control the self-assembly process. In biology, self-assembly is generally dynamic and depends on the cooperation of many such non-covalent interactions. Water can play an important role in these biological self-assembly processes, for example by stabilizing the native conformation of biopolymers(7-9). Hydrogen-bonded (H2O)(n) clusters(10,11) can play an important role in stabilizing some supramolecular species, both natural and synthetic, in aqueous solution. Here we report the preparation and crystal structure of a self-assembled, three-dimensional supramolecular complex that is stabilized by an intricate array of non-covalent interactions involving contributions from solvent water clusters, most notably a water decamer ((H2O)(10)) with an ice-like molecular arrangement. These findings show that the degree of structuring that can be imposed on water by its surroundings, and vice versa, can be profound.