International Hydrographic Organization

The International Hydrographic Organization (IHO) (French: Organisation hydrographique internationale) is an intergovernmental organisation representing hydrography. As of November 2023, the IHO comprised 99 Member States.

A principal aim of the IHO is to ensure that the world's seas, oceans and navigable waters are properly surveyed and charted. It does this through the setting of international standards, the co-ordination of the endeavours of the world's national hydrographic offices, and through its capacity building program.

The IHO enjoys observer status at the United Nations, where it is the recognised competent authority on hydrographic surveying and nautical charting. When referring to hydrography and nautical charting in Conventions and similar Instruments, it is the IHO standards and specifications that are normally used.