Port cities host a rich biodiversity. Protecting it can bring associated positive effects, besides the obvious ones. In Tarragona (Spain), the green areas policy of the port authority is showing excellent results. These areas must reduce the water footprint, promote the biodiversity and mitigate the CO2 emissions. The port has focused on the reforestation of degraded spaces and replacing water intensive plants for others more adapted to the Mediterranean climate. Every year, these areas neutralize 1500 tons of CO2 and provide shelter for endangered species such as bees. In Ceuta (Spain), the Port Authority supports the local Sea Museum (Museo del Mar), that is responsible for studying, protecting and disclosing the local biodiversity. This institution publishes several books and magazines promoting the results of their research, for example on the impact of ships on whales and dolphins. The museum also organizes educational activities and leads projects to include coastal areas in the European networks of protected natural reserves. Additionally, it is responsible for a unique facility, the “pudridero” a facility to preserve the carcasses and collect the bones to study and learn about marine animals.