(Speaking to Noah) Make an ark of cyprus timbers . . . and you shall pitch it inside and outside with pitch. 15. And this is the way you shall make it: The length of the ark shall be three hundred cubits, the breadth of it shall be fifty cubits and its height thirty cubits. 16. You shall make a window . . . and you shall set the door of the ark in the side of it. You shall make it with lower, second and third stories (Genesis 6:14 - 16, HBFV).
Gopher wood's only mention in the entire Bible is in regard to Noah's Ark. This wood could have been the cypress tree used extensively by the Phoenicians. Another possibility is cedar wood. The 'pitch' used was likely bitumen, as there were extensive deposits of it in the Euphrates valley north of Babylon.
The above picture of Noah's ark is a 1/32 scale model. The view shows the interior and the three decks God commanded be made. The inside and outside was coated with pitch. A window was set 18 inches (one cubit or roughly 45.7 centimeters) from the top (Genesis 6:16). Notice the ship's size in the above picture in comparison to the larger animals such as the hippopotamus! Also note the caging system used for the animals.
How BIG was the interior of the ark? God stated its dimensions were to be 300 by 50 by 30 cubits. If we assume a cubit is roughly 18 inches (45.7 centimeters), the ark was 450 feet (137.2 meters) long, 75 feet (22.9 meters) wide and 45 feet (13.7 meters) high. The volume of the ship would be 1,518,000 cubic feet. The actual floor space would be more than 101,000 square feet (9,383 square meters)!
Noah's Ark was crafted to be big in order to survive the flooding of the ENTIRE surface of the earth with water. Although some theologians believe the flood was local in nature (occuring only in the area of Mount Ararat, where the ship ultimately grounded) such conclusions make no Biblical or geological sense.
"There are at least thirty such expressions of cataclysmic universality in the biblical record of the Flood . . . Biblical references to the Flood are not limited to the early chapters of Genesis but also occur frequently in later parts of the Bible (Psalm 29:1 - 11, Isaiah 54:9, Matthew 24:37 - 39, etc.), and all those passages can only be understood in the context of a universal Flood.
"Even if only the mountains in the immediate vicinity of the mountains of Ararat on which the ark grounded when the waters began to recede after 150 days of rising (Genesis 7:24 - 8:5) were covered, it would not have been possible for the floodwaters to be retained in the local vicinity. The present Mount Ararat is seventeen thousand feet high, and it was two-and-a-half months after the ark grounded before the tops of any mountains could even be seen . . . To imagine that a year-long, seventeen-thousand-foot high flood could have been a local flood is absurd." (Science and the Bible by Henry M. Morris, chapter 3).
On a final note, only air breathing, land based animals were taken inside Noah's Ark (see Genesis 6:17,19 - 20, 7:22). Animals like whales, dolphins, alligators, fish, turtles, lobsters, and so on did not need saving from the flood since they already could live in water!