Panthalassa

Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek πᾶν "all" and θάλασσα "sea"),^[1] was the vast superocean that encompassed planet Earth and surrounded the supercontinent Pangaea, the latest in a series of supercontinents in the history of Earth. During the Paleozoic–Mesozoic transition (c. 250 Ma), the ocean occupied almost 70% of Earth's surface, with the supercontinent Pangaea taking up less than half. The original, ancient ocean floor has now completely disappeared because of the continuous subduction along the continental margins on its circumference.^[2] Panthalassa is also referred to as the Paleo-Pacific ("old Pacific") or Proto-Pacific because the Pacific Ocean is a direct continuation of Panthalassa.