The OpenSeaMap server attempts to create free marine charts for the world. Quoting from their site:
OpenSeaMap is an open source, worldwide project to create a free nautical chart. There is a great need for freely accessible maps for navigation purposes, so in 2009, OpenSeaMap came into life. The goal of OpenSeaMap is to record interesting and useful nautical information for the sailor which is then incorporated into a free map of the world. This includes beacons, buoys and other navigation aids as well as port information, repair shops and chandlerys. OpenSeaMap is a subproject of OpenStreetMap and uses its database.
Click here to download OpenSeaMark.tltx