What are Notices to Mariners?

The situation at sea changes continuously. The Hydrographic Service monitors changes and publishes the necessary corrections to its publications in order to give mariners information about the current situation. It does so by issuing Notices to Mariners.

Do you see uncharted dangers, changes or errors in nautical charts? E-mail to hydro.admin@mindef.nl.

Corrections to nautical charts and publications

Notices to Mariners (NtM) are corrections to nautical charts and publications. NtM only contain information which is vitally important to safety at sea. Mariners are obliged to keep their products up-to-date with NtM until a new edition is issued. NtM only apply to editions in force. As soon as an edition is cancelled it is no longer possible to correct this product with an NtM. You should always use the latest edition of a chart or publication.

Further information

The brochure ´BaZ in kaart gebracht´ provides a comprehensive explanation of NtMs (only available in Dutch). In addition, there is the NtM1, a yearly publication containing NtM related and general nautical information.

Where can you find NtMs?

Notices to Mariners are published weekly and are available in the following forms:

Please report omissions

If you discover any uncharted dangers, changes, or errors in our products, please let us know by sending an e-mail to hydro.admin@mindef.nl.


Every coastal state is obliged to chart its coastal waters and make these data available. As a mariner, you must use these official nautical products. This obligation ensues from the International Convention for the Safety of Life at Sea (SOLAS Convention).