africa american geographical society americas anglo-america antarctic circumpolar current antarctica arabian peninsula arctic arctic ocean asia asia-pacific atlantic ocean australasia australia bering strait cape agulhas cape horn caribbean caucasus central africa central america central asia central europe classical antiquity continent continental drift earth east africa east asia eastern europe europe far east greenland hydrosphere iceland india indian ocean indochina iranian plateau latin america levant maghreb malay archipelago melanesia mesopotamia micronesia middle east north africa north america north asia north pole northern america northern europe ocean ocean world oceania oceanography oceanus origin of water on earth pacific ocean plate tectonics polar region polynesia russia scandinavia sea sea ice seven seas siberia south america south asia southeast asia southern africa southern cone southern europe southern ocean southwest asia subregion superocean water west africa western europe world ocean atlas yuly shokalsky