The location of a town or city that is on the coast of a sea, ocean, or even by a major river which provides a harbor for ships, etc.: Doug was planning to sail on a container ship, or freighter, from a seaport on the Mediterranean Sea.

Rotterdam is a seaport in the South West Netherlands; the second largest city of the Netherlands and one of the world's largest seaports with oil refineries, shipbuilding yards, etc.

Boston is a major seaport on the Atlantic Ocean in the northeastern part of the United States.