In times of environmental degradation and depletion of land, large scale ocean farming of seaweeds, so-called seaweed culture, has lately been examined as a possible problem solver of the climate crisis. However, to understand the role of seaweed today one needs to get immersed in a complex nexus where various scientific, environmental, commercial, social and cultural interests merge. From the interdisciplinary registers of feminist blue humanities this article investigates the potential of what is here referred to as 'feminist seaweed cultures' acknowledging environmental ethics and entanglements between humans and seaweeds in art and science. The analysis of visual artworks by ikkibawiKrrr, Ingela Ihrman and Matthew Bennington & Tom Pope opens a portal into the life and work of female seaweed pioneers active in Korean and British waters; namely the sea women haenyeo and botanists Margaret Gatty and Anna Atkins. Through proposing 'feminist seaweed cultures' as analytical tool the aim is firstly to reconceptualize seaweed as a product in aquaculture, and second to focus on visual ecological art to investigate how such artworks may deepen and make human relations to seaweed more ethical, generative and ambivalent. The findings indicate that the work of both the contemporary artists and the historical collectors can be described as feminist seaweed cultures, however in different ways. The ethical and situated perspectives provided by feminist seaweed cultures can thus foster new and old alignments between humans and seaweeds, art and science, land and sea, to support various ways of living well together in times of environmental disruptions.