General Reference: Maps

The historical map collection has over 28,000 maps and images online. The collection focuses on rare 18th and 19th century North American and South American maps and other cartographic materials. Historic maps of the World,Europe,Asia, and Africa are also represented. (from the site)

From the Library of Congress

Provides access to e-copies of the traditional folded maps in magazine supplements of National Geographic.

From the USGS site, find maps and related data about geology, inclulding marine geology.

Tides and currents charts available here from NOAA.

From the University of Texas.