The World-Wide Navigational Warning Service (WWNWS) is a co-ordinated global service for the promulgation of navigational warnings. WWNWS is established through the joint efforts of the International Hydrographic Organization (IHO) and the International Maritime Organization (IMO). These navigational warnings form part of the Maritime Safety Information (MSI) and are broadcasted via NAVTEX and SafetyNET.
Navigational warnings are of three types:
Under this system the world's oceans are divided into 16 areas, called NAVAREAs and identified by Roman numerals. WMO uses the same areas for their meterological warnings.