Genesis 7:4 - For yet seven days, and I will cause it to rain upon the earth forty days and forty nights; and every living substance that I have made will I destroy from off the face of the earth.
The ark had only one door, symbolic of Christ who is the only door to reach God. There came a day, prior to the flood, when they were told to enter the ark, and shut themselves in.
Just as Noah was able to rest within the ark, secure from the waters of death, so we can be assured of spiritual rest, for our lives are hidden with Christ in God.
The ark was a secure refuge from certain death; it was a type of Christ, who provides spiritual refuge for all believers. Noah's obedience to the command of God to build and enter the ark typifies the believer who, by faith, receives Christ and is saved from judgment (spiritual death).