The oceans were formed by the large plates of land and the mantle underneath. It formed a huge hollow in which water could accumulate. By tectonics and deposits created sea ridges, ditches, rocks / sediments and basins. The first sea creatures were simplest bacteria and other protozoa. Until the year 2009 and the World Oceans conference (WOC) in Indonesia a lot has happened. Change of concept with time Among other things, the Greeks already knew the Red Sea, the Mediterranean, the Persian Gulf, the Adriatic and the Indian Ocean. Furthermore, you subdivide the Mediterranean Sea into Adriatic Sea, Ionian, or Thyrranian Sea. The concept of the ocean was really shaped and widely known through the discoveries of the late Middle Ages / Renaissance (12th-15th c.). So the Chinese, Caribbean and Caspian Sea as well as the North / Baltic Sea and the Red Sea were considered as the oceans. With the advent of the Renaissance and modern times (until the 17th century), the picture changed again. The Pacific Ocean, the Atlantic Ocean, the Indian Ocean and the Arctic Ocean were counted among the oceans, which gave rise to the current picture of the oceans and the ocean, as we know it today. The World Ocean Conference did not make much difference here: all parts of the world were in the interest here. from which emerged the current picture of the oceans and the ocean, as we know it today. The World Ocean Conference did not make much difference here: all parts of the world were in the interest here. from which emerged the current picture of the oceans and the ocean, as we know it today. The World Ocean Conference did not make much difference here: all parts of the world were in the interest here.