Transitional territories such as lagoons are among the most impacted and delicate environments, threatened by the combined effects of climate change and human action. This Master thesis in Landscape Architecture examines the Venetian Lagoon in North of Italy as one of the most endangered and critical cases, as the last extreme flooding event of November 2019 demonstrates. The thesis aims to address the Venetian Lagoon hydromorphological sufferance, the state of neglection of its secondary islands, and the over-engineered flood defence design as crucial issues. From the research conducted, emerges clearly the need for redefining the role of the entire Venetian Lagoon in the next future, shifting its role from passive, being exploited and consequently damaged, to active, able to sustain resiliently the rest of the territory. In order to do so, the main strategy to be pursued is to reinforce the “barene” landscape, the brackish marshlands, fundamental for the hydromorphological and ecological survival of the lagoon. These brackish marshlands are able to limit tidal and wind impact, favour water exchange and act as an expansion vessel, but, from 20th century onwards, 70% of their surface have been lost due to anthropic actions. Therefore, the goal of the thesis is to employ the agency of “barene” to mitigate the impact of anthropic and natural threats, acting as a nature-based flood defence (function), to recover hydromorphological sufferance (flow), and to support the cultural, ecological and productive heritage (form), making the Venetian Lagoon function as a sustaining landscape infrastructure. The “barene” act as pivotal means to achieve a comprehensive vision for the Venetian Lagoon where functions, flows, and forms are implemented and designed as part of a unique co-operating system. The central area of the Venetian Lagoon is chosen as project site, being the most damaged hydromorphologically. Having researched on how natural forces (tides, winds, etc.) influence this portion of lagoon, different combinations of under-water and above-water concave structures are designed in harmony with these forces, to capture suspended sediments and promote accretion. In the most compromised cases, the structures are partially supported by initial dredges. The islands of the central lagoon become the perceptive points from which experience the transformation and the growth of this new landscape. In the end, the intertwined system of “barene” and islands, once grown sufficiently and matured, will produce a beneficial effect over the hydromorphological, ecological and biodiversity, and cultural surrounding environment. Through the process of research by landscape design, the project seeks to mitigate the threats of climate change and relative sea level rise in the Venetian Lagoon; provide a nature-based flood defence; create brackish marshland’s habitat for ecosystem restoration; invest on alternative forms of slow-tourism and foster different duration of stay in Venetian lagoon; enrich local community livelihood and economical vibrancy. Moreover, the project wants to consolidate and enhance the cultural image of the Venetian Lagoon, consisting of the diffuse sense of horizontality, reflection and visibility conveyed by the diffuse and unceasing water surface.