Floating and hanging structures add variation to otherwise smooth underwater environments and provide artificial substrates for habitat creation. These installations promote settlement to enhance the population of filterfeeders and provide fish habitats, thereby improving biodiversity. Filterfeeders contribute to improved water quality, often a significant motivation for action in cities. Two further benefits are new opportunities for recreational fishing and the potential for wave attenuation where structures have grown heavy with marine life. The structures are relatively easy to apply and offer opportunities for added services even when physical conditions or design constraints require hard solutions and/or provide little space for Building with Nature.