Time travel
Let’s say you could travel back in time to Noah’s generation.
The only thing you can take with you is some clothing, food, and a book without pictures stating that man has been to the moon. When you arrive at Noah’s generation you get dropped off there for a couple of days.

As you stay, you meet some people and then you tell them that man has been to the moon and you showed them the book with the written proof. After you told them that man has been to the moon they started to laugh at you and mock you saying, 
“It is impossible for man to go to the moon, you are crazy that could never happen.” With this example, it is no different in trying to convince people in Noah’s generation that man has been to the moon and the people in our generation who refuse the fact of the story of Noah’s ark.
Real life size Noah's ark in Williamstown, KY 
Global proof the world was flooded with water
Water sedimentary in mountains all over the world.

Marine fossils on top of mountains all over the world
In the beginning before the flood the scripture teaches us that the ocean was all one big massive sea while the land was one big mass as recorded in
Gen 1:9-10. NKJV  “Then God said, “Let the waters under the heavens be gathered together into one place, and let the dry land appear”

This tells us that the dry land appeared in one place while the sea
around it was one huge massive sea.

Scientists agree that at one time in history the
earth was a Pangea.
Just right after the flood of Noah scripture teaches us that the land was divided in Genesis 10:25.

NIV "Two sons were born to Eber: One was named Peleg, because in his time the earth was divided; his brother was named Joktan."

When God flooded the earth, under the water the land (divided) while Noah and his family with the animals were floating on top of the water. 

When the waters receded from the dry land after the flood the earth had already been divided and it gives us what
we have today.
How did the Kangaroo get to Australia after the flood? 
After the flood there were land bridges that connected many of the continents, and since the land was divided under the flood, the sea levels were lowered when the water receded making land bridges for the Kangaroo to get to Australia.
Now since Noah’s flood rose above mountain tops and water covered the earth, much of that water froze into huge mountains of glaciers in cold climate conditions like the North Pole and surrounding areas. Many years later, the glaciers from those cold climates started to melt and the sea water level rose. This caused many land bridges to disappear.
 Gen 6:19 "And of every living thing of all flesh, two of every sort shalt thou bring into the ark, to keep them alive with thee; they shall be male and female."
Noah’s ark is 510 feet long making the length of one and a half football fields. The height of the ark is 50 feet making it around 5 stories tall. This actually makes the ark have the storage room of 450 semi-trailer or 18 wheelers.

With this in mind, Noah could easly fit all the animals on the ark that were much y ounger and smaller.  
How did Noah fit all the animals on the ark? 
Why did God flood the earth?
Genesis 6:5 NLT “The LORD observed the extent of human wickedness on the earth, and he saw that everything they thought or imagined was consistently and totally evil.”
Genesis 6:11-13 KJV “The earth also was corrupt before God, and the earth was filled with violence. And God looked upon the earth, and, behold, it was corrupt; for all flesh had corrupted his way upon the earth.”

The world was filled with such violence that God flooded the earth before mankind could kill each other untill no one was remaining.