Running the applet on this page used to be a lot easier before the new locked down security configuration of Java. If you have Java on a Windows computer, you may need to go to Control Panel -> Java and add or as an exception under the Security tab. Then, reloading this page, you may still need to enable the Java plug-in (this is browser dependent) and then allow Java to run the applet. If this sounds more complicated than it's worth... I hear you. One of these days, I will write a JavaScript version of this applet, doing away with the need to use any plug-ins.

NB: Java applets no longer work at all in the Chrome browser, as support for such plugins was discontinued by Google.

Astronomers of the past have named large, flat areas on the Moon's surface Mare, Latin for Sea. Whether or not they actually believed that these were real seas on our satellite, we now have the means to see what the Moon would look like, were it actually partially covered with water. The interactive map below uses altitude data from NASA's Clementine mission.

To use this program, set the sea level altitude to the level of your choosing (meaningful values are between -5000 and 10000 meters), and click the Redraw button. On slower computers, it may take a bit of time for the map to update itself.

Sea level altitude: meters.