Notices to Mariners contain important navigational information. This includes chart updates, changes in buoyage warning of activities such as dredging. Notices to Mariners are issued by several organisations, including the UK Hydrographic Office (UKHO), Trinity House and local harbour authorities. You can often find Local Notices to Mariners online, and many harbour authorities provide email updates you can subscribe to. ADMIRALTY Small Craft Chart Service, a division of the UK Hydrographic Office, provides regular Notices to Mariners for keeping Small Craft Charts up to date. You can find information on the ADIMRALTY Small Craft Charts web page. Imray has a similar corrections service on its website. To know more select: PRESENTATION