This chapter explores the multifaceted roles and benefits of seaweed in temperate regions, with a particular focus on Portugal. Seaweed are highlighted as crucial ecological assets, contributing to marine biodiversity, coastal stabilization, and carbon sequestration. Their ability to absorb excess nutrients from agricultural runoff helps mitigate eutrophication, thereby maintaining coastal ecosystem health. In agriculture, seaweed are presented as sustainable resources that enhance soil fertility, stimulate plant growth, and improve crop resilience through the use of bio-fertilizers, reducing reliance on synthetic alternatives. The chapter also delves into the biotechnological and industrial applications of seaweed, emphasizing their adaptability to temperate climates and their potential for large-scale cultivation. Seaweed provide renewable biomass for various industries, including food, cosmetics, and biotechnology, supporting both environmental conservation and the economic viability of coastal communities. A significant portion of the chapter is dedicated to the culinary and nutritional value of seaweed. Workshops like “Algas à Mesa” have promoted seaweed as a versatile ingredient in Portuguese cuisine, showcasing its health benefits and culinary potential. Recipes such as “Seaweed and Cod Fritters” and “Seaweed Risotto” illustrate how seaweed can enhance traditional dishes while aligning with sustainable gastronomic practices. By integrating seaweed into sustainability initiatives, the chapter underscores their importance in supporting environmental conservation and economic resilience. Through Portuguese examples, the chapter highlights the diverse applications and benefits of temperate seaweed, advocating for their broader use in sustainable practices.