How did all the animals fit into Noah's ark? During the great flood Noah was ordered by God to fetch two animals of each species and put them into his ark. 


  19    And of every living thing of all flesh, you shall bring two of
  every kind into the ark, to keep them alive with you; they shall be
  male and female.  
  
  20    Of the birds after their kind, and of the animals
  after their kind, of every creeping thing of the ground after its
  kind, two of every kind will come to you to keep them alive.  
  
  21    As
  for you, take for yourself some of all afood which is edible, and
  gather it to yourself; and it shall be for food for you and for them.


Genesis 6:19-21

There are more than 1 million different species of animals in existence (that we know of), many of them are quite large or dangerous. How can all of those animals even fit into the ark, together with the vast amounts of food that would be needed?
I suppose there is one other possible answer:


  It was a miracle.


That would put it in the "how did Jesus walk on water?" and "how did Jesus feed thousands of people with a few fish sandwiches?" category.