"And God said to Noah, 'The end of all flesh has come before Me, for the earth is filled with violence through them; and behold, I will destroy them with the earth. Make yourself an ark of gopherwood; make rooms in the ark, and cover it inside and outside with pitch. And this is how you shall make it: The length of the ark shall be three hundred cubits, its width fifty cubits, and its height thirty cubits. You shall make a window for the ark, and you shall finish it to a cubit from above; and set the door of the ark in its side. You shall make it with lower, second, and third decks'" (Gen. 6:13-16).
Noah and his family would be saved from the global deluge by God's grace through their obedient faith (cf. Eph. 2:8,9). God intended to destroy life with the Earth itself (i.e., the water). In so doing, He would destroy the Earth itself to a degree (or at least the unique environment He had initially created). After the flood, many things would be different (e.g., life span, diet, environmental conditions, rain, etc.). God specified that the ark was to be made of gopherwood and covered with pitch (to seal it and make it water-ready). The dimensions of the ark would be approximately 450 feet long by 75 feet wide by 45 feet tall (based on a "cubit" of 18 inches in length). That's as long as 1.5 football fields! The capacity of the ark would be equivalent to over 520 railroad boxcars! In other words, the ark was huge! Could four men have built such a boat in less than 100 years? Could this vessel have carried all of the animals it needed to? Could eight people survive on a boat for a year and sustain thousands of animals? Could this boat actually float? The answer to all of these questions is a resounding "Yes!" Although it is beyond the scope of our current study, there are good books that have been written asking and answering questions just like these about the feasibility of all aspects of Noah's ark. Recently, I viewed a DVD presentation on the global flood by Brad Harrub that was well done. It is a good addition to any library and currently available from www.FocusPress.org. One of the fascinating aspects of the DVD is the information from World War II about a ship known as "The Ugly Duckling," which was built in America to the dimensions of Noah's ark. It wasn't built for speed, but it floated and was exceedingly stable and able to carry large amounts of cargo.
"And behold, I Myself am bringing floodwaters on the earth, to destroy from under heaven all flesh in which is the breath of life; everything that is on the earth shall die. But I will establish My covenant with you; and you shall go into the ark--you, your sons, your wife, and your sons' wives with you. And of every living thing of all flesh you shall bring two of every sort into the ark, to keep them alive with you; they shall be male and female. Of the birds after their kind, of animals after their kind, and of every creeping thing of the earth after its kind, two of every kind will come to you to keep them alive. And you shall take for yourself all food that is eaten, and you shall gather it to yourself; and it shall be food for you and for them.' Thus Noah did; according to all that God commanded him, so he did" (Gen. 6:17-22).
With God all things are possible, even the amazing task outlined above. It should be noted that every kind of animal would be on board (that's not the same as every species necessarily). God would certainly help bring animals to Noah for the preservation of their kind. The chapter closes with a wonderful testimony to Noah. He obeyed in everything that God had instructed him to do (which implies his great faith in laboring many decades on a boat of this magnitude). We today need to have this type of faith--faith that obeys (cf. Heb. 11:7)!