The Harbour Fort

From publisher blurb:

Guarding the entrance to the important harbour of Kittlesea, the fort was built to deter pirates and other raiders from preying on the merchantmen that bring holds full of expensive cargoes.
A printable rpg battlemap compatible with any RPG/Dungeon-Crawl or skirmish game. Use as a standalone gameboard, or combine with any same-scale tileset. The map is 50x50, equivalent to 25 of our standard 10x10 tiles.

Contents: A strong fort built by the entrance to a harbour which sits a mile inland. This fort is the primary defence, and has strong walls and battlements. A chain is stretched across the channel, and can be lowered to allow access.