on the seventeenth day of the second month: This specific detail gives the flood account a sense of seriousness. It shows that the event is presented as something that happened in history.
fountains of the great deep: See 2:6.
the floodgates of the heavens were opened: The great flood undid the boundaries established on the second and third days of creation (1:6–13). Other parts of the Bible describe God's judgment as undoing creation (see Jeremiah 4:23–26; Amos 7:4).
forty days and forty nights: See study note on 7:4.