The kelp Saccharina latissima is an economically important edible seaweed with great potential for use in other applications. The goal of this study was to identify locations in a coastal bay with better conditions for commercial cultivation of this species. We compared the biomass yield and morphological features of S. latissima cultivated at two locations in a bay of Galicia (northwest Spain): in an external moderately exposed site and in an internal sheltered site. Biomass yield was significantly higher at the moderately exposed site than at the sheltered site (16 fresh kg vs. 12 fresh kg per linear meter of rope). Fronds were significantly larger at the moderately exposed site compared to that at the sheltered site. However, the “substantiality value” (around 40 mg cm?2), which is an index used to assess blade quality for human consumption, did not differ significantly between the two locations. The effect of light exposure and water velocity seemed to be the most important environmental factors that explain the differences in the results obtained at both culture sites. In summary, both the moderately exposed site and the sheltered site were suitable for cultivation of S. latissima, as indicated by the high yields and similar blade quality obtained at both locations.