The Atlas Ocean (analogue to the real-world Atlantic Ocean) is the only known ocean so far in the Ys World. Eresia and Afroca are located at the east of the Atlas Ocean, while the Vortex of Canaan is located at its west edge. The eponymous lost Atlas continent lies at the bottom of the Atlas Ocean. The Eldeen artifact Ark of Napishtim was a weather control device that could control the entirety of this ocean.
Parts of the Atlas Ocean are explored by adventurer Adol Christin in the backstory of Ys VI: The Ark of Napishtim.