In Genesis, how high did the Flood waters rise above the mountains?

In Genesis, the Flood waters rose fifteen cubits above the mountains. Genesis 7:20 states that the waters prevailed fifteen cubits upward, covering the mountains.

The measurement appears after the narrative says that the waters increased and lifted the Ark above the earth. It is a vertical biblical measurement, but Genesis does not define the exact length of a cubit in this passage. Estimates of a cubit vary across historical contexts.

This figure is different from the Ark’s height, which Genesis gives as 30 cubits. It is also different from the duration of the rain and the total period during which the waters prevailed. Those are separate details in the Flood chronology.

Readers sometimes remember fifteen cubits as the Ark’s height or confuse it with the vessel’s dimensions. In the text, fifteen cubits specifically describes how far the waters rose above the mountains.