Genesis 7:18-20

18The waters rose and increased greatly on the earth, and the ark floated on the surface of the water. 19They rose greatly on the earth, and all the high mountains under the entire heavens were covered. 20The waters rose and covered the mountains to a depth of more than fifteen cubits. That is, about 23 feet or about 6.8 meters Or rose more than fifteen cubits, and the mountains were covered