Seaweed absolute brings a deep, green-marine character to perfumery, far more complex than simple saltiness. It smells briny, iodine-rich and vegetal, like kelp beds, tidal pools and wet rocks, with an almost umami depth. In small doses it gives marine fragrances their authentic oceanic backbone; in larger amounts it turns dark and almost leathery. You will find it in serious niche aquatics and some avant-garde green compositions. In India, seaweed-heavy scents are best reserved for coastal summers and experienced noses, they are too challenging for office wear but magnificent on a beach holiday. The iodine facet can amplify in high heat, so apply sparingly. For lovers of true ocean realism rather than pretty aquatics, seaweed is essential.