Firmament - We are trap underwater, deep, very deep down ( en.wikipedia.org )

The concept of the Firmament Solid dome dividing the primal waters comes from ancient beliefs about how the world was created. According to these beliefs, there was a time when everything was covered in water. Then, a solid dome called the Firmament was placed above the waters, separating them into two parts - one above and one below. This idea helped people explain why there is sky above us and why it doesn't mix with the water on Earth.