The National Elevation Dataset is a product offered by the USGS that "is designed to provide national elevation data in a seamless form with a consistent datum, elevation unit, and projection." The interactive GIS map interface can view various layers of data from all over the US, creating informative and useful maps, which can be printed or ordered in CD format. The handy "help" button provides a...

As part of NOAA's National Environmental Satellite, Data, and Information Service, the Laboratory for Satellite Altimetry specializes in the analysis of satellite altimeter data related to problems in physical oceanography and marine geophysics. The Web site provides links to currently active projects with information such as near-real time sea level altimeter data, historical data, European Space...