Question

When did ocean first appear

Answer 1

On day 3 when God said "Let the waters under the heaven be gathered together unto one place and let the dry land appear."

Answer 2

Hello friends...

The ocean formed billions of years ago. Over vast periods of time, our primitive oceans formed.
Water remained a gas until the Earth cooled below 212 degrees Fahrenheit . At this time, about 3.8 billion years ago, the water condensed into rain which filled the basins that are now our oceans.

Hope this answer helps you...