The illustration below is a side-view scale drawing showing the relative size of Noah's ark (450 feet long, 45 feet high - the red line) to a modern-day Boeing 747 airliner (232 feet long, 64 feet high). As you can see, Noah had approximately enough room to have carried not one, but two 747s (with their wings detached and stowed separately) inside the ark!
"Now the earth was corrupt in God's sight and was full of violence. God saw how corrupt the earth had become, for all the people on earth had corrupted their ways. So God said to Noah, "I am going to put an end to all people, for the earth is filled with violence because of them. I am surely going to destroy both them and the earth. So make yourself an ark of cypress wood; make rooms in it and coat it with pitch inside and out. This is how you are to build it: The ark is to be 450 feet [140 meters / 300 cubits] long, 75 feet [23 meters / 50 cubits] wide and 45 feet [14 meters / 30 cubits] high. Make a roof for it and finish the ark to within 18 inches [1 cubit] of the top. Put a door in the side of the ark and make lower, middle and upper decks. I am going to bring floodwaters on the earth to destroy all life under the heavens, every creature that has the breath of life in it. Everything on earth will perish. But I will establish my covenant with you, and you will enter the ark - you and your sons [see Sons Of Noah] and your wife and your sons' wives with you. You are to bring into the ark two of all living creatures, male and female, to keep them alive with you. Two of every kind of bird, of every kind of animal and of every kind of creature that moves along the ground will come to you to be kept alive. You are to take every kind of food that is to be eaten and store it away as food for you and for them." Noah did everything just as God commanded him." (Genesis 6:11-22)
Fact Finder: Did Noah have to go around catching all of the animals, or did God have them come right to him at the ark?
Genesis 6:20 and 7:8-9