That Ark surely is a fable or symbol. Even on the measurements given it could never have contained all said to be in it.

The Catholic Answers

It is not a fable, although it does symbolize the Catholic Church in which souls are saved from the moral flood of sin. It was over 400 feet long, 70 wide, and 40 deep. The flood was most probably local, and the animals were of various types from the region only of its occurrence. We are not obliged to believe that all living animals were represented, nor that all animals outside the Ark were destroyed. Men themselves had not spread so far afield at that time, so that Noah and his family were the sole human survivors. The flood happened; the Ark was a fact; all men were drowned save Noah and those with him in the Ark; that much must be accepted in the literal sense. But many subsidiary details need not be, whilst the wholesale imaginative exaggeration of those details is to be entirely rejected. A thing is credible when a sufficiently capable cause is assigned; incredible if the cause I allege could not do it. But if the cause alleged could do it, then it becomes a question of fact. Did it occur? God says that He caused the flood and its consequences. We cannot say that He is mistaken or deliberately deceiving us. I accept it. You must make your choice. But you have given no sufficient reason for unbelief in your letter.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty