1. navigational aids or landmarks visible from the sea that help ships determine their position or safe passage
Usage: nautical; plural form

Examples

• The lighthouse served as one of the most important seamarks along the rocky coastline.
• Ancient mariners relied on natural seamarks like distinctive rock formations to navigate safely.
• Modern GPS has reduced dependence on traditional seamarks, but they remain crucial backup navigation tools.
• The harbor authority maintains several seamarks to guide vessels through the narrow channel.
• Buoys and beacons are common types of artificial seamarks used in busy shipping lanes.
• Sailors studied their charts carefully, noting all the seamarks they would encounter on their voyage.