Genesis says the floodwaters rose 15 cubits above the mountains.
Genesis 7:20 states that the waters rose fifteen cubits upward and that the mountains were covered. This figure appears in the description of the flood’s greatest extent, after the rain and rising waters had overwhelmed the land.
The passage uses the ancient unit “cubit,” whose exact length varied across cultures and periods. A commonly used biblical estimate is around 18 inches, which would make fifteen cubits approximately 22.5 feet, or 6.9 metres. That modern conversion is approximate rather than exact.
The number is easy to confuse with the ark’s height, which Genesis gives as 30 cubits. It is also separate from the 150 days during which the waters prevailed and the 40 days and nights of rain. Each number belongs to a different detail in the flood chronology.