Sea water is a treasure of many elements and halogens are one of them. It contains many compounds of halogen including bromides, iodides, and chlorides. The solid deposits from sea water contain NaCl and Carnalite. It primarily contains COMMON SALT (2.5% by mass). The deposits of dried up sea bed also contain sodium chloride and Carnallite, KCl.MgCl₂.6H₂O . The Marine life also contains iodine in their systems. For example, sea weed may contain 0.5% iodine as sodium iodide(NaI) and Chile saltpetre (sodium compound) contains about 0.3% of sodium iodate.

Thus, the sea is the greatest source of halogens.