Hydrographic office

A hydrographic office is an organization which is devoted to acquiring and publishing hydrographic information.

Historically, the main tasks of hydrographic offices were the conduction of hydrographic surveys and the publication of nautical charts. In many countries, various navigation-related services are now concentrated in large governmental organizations, sometimes termed "maritime administration" (however, the International Hydrographic Organization uses the term "hydrographic offices" for its member organizations).

Besides nautical charts, many hydrographic offices publish a body of books and periodicals that are collectively known as nautical publications. The most important of these are:

• Sailing Directions (or pilots): detailed descriptions of areas of the sea, shipping routes, harbours, aids to navigation, regulations etc.
• lists of lights: descriptions of lighthouses and lightbouys
• tide tables and tidal stream atlases
• ephemerides and nautical almanacs for celestial navigation
• Notice to Mariners: periodical (often weekly) updates and corrections for nautical charts and publications

Hydrographic organizations may also be involved in services such as:

• pilotage
• search and rescue
• maintenance of lighthouses and other aids to navigation
• ice breaking
• weather observation and information
• sea traffic information and surveillance
• maritime research
• regulatory affairs of ship safety