Mare clausum defended a "Mare clausum" policy during the age of discovery. This was soon challenged by other European nations. From 30 BC to 117 AD the Roman Empire came to surround the Mediterranean by controlling most of its coasts. Romans started then to name this sea "mare nostrum" (Latin for "our sea"). At those times the period between November and March was considered the most dangerous for navigation, so it was declared ""mare clausum"" (closed sea), although bans on navigation were probably never enforced. In classical law the ocean was not territorial. However, since the Middle Ages maritime republics like the
Mare Cognitum Apollo 12 demonstrate that the volcanic activity that formed the lunar mare did not occur all at once across the lunar surface, but rather took place at different times at different locations. Mare Cognitum Mare Cognitum ("The Sea that has Become Known") is a lunar mare located in a basin or large crater which sits in the second ring of Oceanus Procellarum. To the northwest of the mare is the Montes Riphaeus mountain range, part of the rim of the buried crater or basin containing the mare. Previously unnamed, the mare received its name in 1964 in reference to its