Bromophenol: It is for this chemical compound that the sea has the strong odor of iodine. This is the scent that molluscs and crustaceans also carry with them due to the fact that they feed on algae and other organisms found in the seabed.

The "scent of the sea" is often described as smelling like iodine, but the actual chemistry behind that distinctive aroma is more complex. While the ocean does contain iodine, the characteristic pungent, salty smell is primarily caused by a chemical called Dimethyl Sulfide (DMS). DMS is produced by bacteria that digest dead phytoplankton and algae; it is a "sulfurous" odor that, in low concentrations, creates that refreshing sea breeze scent. Another contributing molecule is Bromophenol, which is found in many marine organisms like fish, mollusks, and seaweed; in higher concentrations, bromophenols have a medicinal odor that is almost identical to pure iodine. Additionally, algae produce pheromones called Dictyopterenes, which add a sweet, earthy note to the mix. So, while you are not literally smelling "iodine" in its elemental form, you are smelling a cocktail of biological byproducts that trigger the same sensory response. This scent is actually a vital "food map" for seabirds, who follow the smell of DMS to find areas of the ocean teeming with fish and plankton to hunt.