Explore Local Notices to Mariners on the map

What are Local Notices to Mariners?

Local Notices to Mariners, often shortened to LNMs, report changes, hazards, and activities affecting navigation. In the United States, the Coast Guard publishes them for the waters under its districts’ jurisdiction. They cover temporary conditions as well as lasting changes.

They’re useful for a weekend on the boat as well as a longer coastal passage. Even on a familiar route, a notice about bridge work may affect your timing, while reported shoaling may matter to your boat’s draft.

What can a notice tell you?

• Navigation markers: a light is out, a buoy has moved, or an aid to navigation has changed.
• Hazards and depths: an obstruction has been reported, a channel has shoaled, or depths have changed.
• Work on the water: dredging, marine construction, or bridge work may affect passage.
• Events and restrictions: a marine event or safety zone affects a particular area or time.

The details matter. A notice’s location, dates, and instructions help you work out whether it affects your plans.

Put notices in the context of your trip

Seaward brings notices onto the map you use to explore your trip. See where a notice sits relative to your harbor or approach, then open its details without leaving the map.

Browse the area you care about

Find notices around your harbor, its approaches, and the waters along your planned trip. See their locations in relation to where you’re going.

Choose which notices to show

Focus on the notice categories relevant to your plans, from navigation markers to work on the water.

Read the details in place

Read notice descriptions, dates, and waterway details where supplied, without losing your place on the map.

For background on a harbor or approach, explore Seaward’s Coast Pilot guide. It complements notices with descriptions of coastal waters and places.