In the South Pacific Islands, seaweeds have long been used as food, medicines and ceremonial objects. Throughout the region, human consumption of seaweeds is widespread (mainly Caulerpa) and, nowadays, few species have been cultivated for phycocolloid industry (Eucheuma, Gracilaria, Kappaphycus). These tropical seaweeds also contain an extremely important chemodiversity (mainly terpenes, alkaloids, halogenated and phenolic compounds) representing an original and innovative resource that is not exploited until now. In French Polynesia, several research programs are conducted to explore the diversity of marine algae as a source of biotechnological applications. Extracts from 30 marine macroalgae species (10 Chlorophyta, 11 Phaeophyceae, and 9 Rhodophyta) and 10 benthic cyanobacteria from French Polynesia were evaluated for several biological activities. Some species could be used in cosmetic products for their potent antioxidant activities (Amansia rhodantha, Sargassum pacificum), other could be used in aquaculture for their strong antimicrobial activities against two pathogens Tenacibaculum maritimum and Vibrio harveyi (Dictyota bartayresiana). Furthermore, the French Polynesia politics aims for several years to develop insular rural seaweed farming (mainly Caulerpa and Gracilaria), and some co-culture projects (shrimps/seaweeds or fish/seaweeds) are emerging. These researches could offer interesting socio-economic opportunities for French Polynesia in the cosmetic, food, agricultural and aquaculture industries