The upper limit of the earth's atmosphere is about 2000~3000 meters high. If you think so, it is outer space, not the sky, so the sky is 2000~3000 kilometers high.
But if you think about it from another angle, the height of the sky is infinite, because the universe is infinite.
The deepest part of the ocean, the Mariana Trench in the central Pacific Ocean, has a depth of10911m. 。