The area off-shore Venice is characterized by a relatively mild climate that allows in principle a safe installation of an off-shore platform, but at the same time strongly limits the benefits of a single-purpose installation, both because of the limited available energy and because of the high distance from the shore due to the flat sea-bottom. Therefore the site appeared to be suited for multi-purpose designs with fish farming and wind energy as potential activities. An Ecosystem Services Approach (ESA) is adopted to identify possible environmental effects and conflicts with other relevant uses. We deal with these potential impacts by choosing a suitable location of the platform. Limited financial data on wind energy suggested a negative Net Present Value (NPV), whereas proper financial data on fish farming produced a slightly positive NPV. A Life Cycle Assessment applied to wind energy and fish farming estimated a significantly positive effect from reduced CO2-eq emissions expressed in euros. A Social Cost-Benefit Analysis (SCBA) applied only to fish farming (i.e., including financial and CO2 results) due to lack of data and resulted on a positive NPV. However, a MUP is not recommended by SCBA, and more explicitly it is not supported by stakeholders in the short-run. Whereas, it might be suggested in the long-run, when, in a crowded sea, both economic and environmental reasons could suggest to move some activities off-shore.