In the Christian Bible story, Noah built an ark that could hold two of every land animal. Now let's assume that Noah lived in 3000 BC and that he had the men and materials to build this boat. How large would it be? The only rule is that Noah needs to be able to build it using technology from that time and every animal in the phylum vertebratae needs to be able to live on it for a long period of time. We can also assume the carnivores eat the floating corpses of sinners. Unlike in This Question, he can take the easy way out, putting them in stalls.

  • How long would it take take if only him and his three sons works on it what about if a small village of 40 helped them?
  • How big would the boat need to be?
  • How long would it take to round up all the animals?

Also, forget about realism when it comes to time; we all know how extremely unlikely it is they would be fast. If the answer is that it will take 80 years, then so be it. Noah can pass on the task and God will talk to his descendants.

A list of Can We Build question can be found here

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    $\begingroup$ The Bible actually specifies the size of Noah's Ark. Wikipedia has it in modern units of measurement; "approximately 137m long by 22m wide by 13m high (450 feet long by 75 feet wide by 45 feet high)." This doesn't answer your questions, but it's an interesting reference point. $\endgroup$
    – user6511
    Commented Oct 20, 2015 at 0:18
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    $\begingroup$ A lot of creationistist assume Earth was a single continent as this simplifies the collection of animals considerably. Are you ruling single continent or essentially the curent continental and animal distributions. $\endgroup$ Commented Oct 20, 2015 at 2:47
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    $\begingroup$ The biggest reason it's not going to work is that "the technology of the time" simply did not allow for ships this big. There's a hard limit on how large a wooden ship can get and even the biblical Ark exceeded it. $\endgroup$
    – Erik
    Commented Oct 20, 2015 at 6:24
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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ Commented Oct 20, 2015 at 19:37
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    $\begingroup$ Do freshwater fish have to be in tanks on board, or has the rain kind of made the ocean a brackish mix? $\endgroup$
    – Mikey
    Commented May 16, 2016 at 18:57

3 Answers 3


My understanding of your rules:
A. Transport two of every (non-fish) vertebrate to Iraq.
B. Put them on a boat that would fit them all.
C. Do this using only historically reasonable technology, with no additional divine intervention.

Rule C is important, because once we allow magic, what's the point in asking the question? Any omnipotent deity who really cared could have poofed the boat and animals into existence instantly and skipped the entire silly story. I will, however, assume that the animals are willing participants in this process though - that once Noah reaches their range, he won't have to find and trap them. If not, I'm fairly certain that the process couldn't be completed by Noah and his family ever.

  1. Building the boat would have required a substantial amount of time. Some creationist types have put construction time at between 70 and 120 years. Recall that Noah and co. were supposed to have lived for several hundred years. There are massive logistical problems with building the biggest wooden vessel ever constructed in ancient Iraq, not the least of which is supplies. The sheer amount of wood required to build the vessel is enormous - it would have had to have been imported to the area from elsewhere.

  2. Most of the vertebrate species on Earth are quite small. For instance, the vast majority of the 6000 amphibian species would, if placed in containers roughly the size and shape of 10 gallon aquariums, fill a volume of about 120'x15'x8' (40 3' wide shelves that are 15' wide and 8' high, crammed full of aquariums with just enough space between shelves to walk. If you could just throw all the frogs in a bucket together, then you can collapse this down substantially, of course. All but a few of the amphibians would fit into such a container easily.

    The other groups of vertebrates are similar, with most members fitting comfortably in a breadbox sized volume, but there are as many as a thousand species that need considerably more room. It's also difficult to count how many species there really are. For instance, the number of extant Equus species (horses and friends) is anywhere from 7 to 24, depending on how you count them. Monitor lizards dragons, the big cats, anacondas, pachyderms, and large primates are all problematic in this regard, and there's no good way to count them up by volume. If we give each of them a goat-sized stall (5'x8') and assume that the ones that are a little smaller will average out with the ones that are a little bigger, then considering all of the larger animals on the planet, you're looking at something like 40,000 square feet of floor space. With enough room to walk between stalls for feeding, the big animals would fill up about one and a third entire floors of the biblical ark. The non-fish vertebrates would have fit into the ark, barely.

    I initially thought that packing sufficient food for the trip would be problematic, but it is less so than I originally thought. The elephants would eat about 500 pounds of high quality food per day. The voyage was roughly a year long (a bit more if you add up all of the days) so that is roughly 70 tons of elephant food alone, another 70 cubic meters of space (assuming the food is packed extremely efficiently.) Food for a similar duration of the trip for all of the other animals would be problematic to collect, and for herbivores, the food will take up a substantial amount of space as well, though there is no reason you couldn't put that food in the enclosure with the animals. Gaining access to sufficient quantities of fresh water for all of the animals would be a challenge though.

    Now, could you cram all of the animals into smaller enclosures and have plenty of room? Of course you could, and if we're assuming divine intervention to deal with all of their behavior for the collection and trip, it might be appropriate to do so. In any case, the biblical dimensions, perhaps with some additional height added so that we can get three floors into it if needed, should be sufficient to hold the vertebrates and a year's worth of food.

  3. Using your rules, it would take a very, very long time and be exceedingly difficult. Any voyage would have been done by sea or caravan overland, and the logistics of moving that many animals to Iraq are daunting at best. Basically you'd have to build arks just to collect the animals to go on the ark. That is going to take years itself.

    The bigger problem is speciation. New species arise at a rate of roughly 1-3 per million per year. We'd expect as many as one new vertebrate species each decade. Columbus's trip took about a year, with essentially no overland travel involved. Magellan's crew got back after 3 years, again without significant overland travel. Lewis and Clark took 2 years to walk a single line across the continental US. Each new species that arose would set Noah back by years, and the time required simply to sail to every single required landmass on Earth would be astounding. I honestly don't know how to put a number to it. You also introduce the horrible logistics of caring for enormous numbers of animals while you wait for Ham to get back with the latest variety of leopard frog or whatnot.

    This amount of time is entirely dependent on the level of magic we're willing to accept. If the animals are not cooperative, then the collection will take forever due to speciation. If the animals are super cooperative, traveling to easy to reach ports for collection, then it might just be possible over the course of several decades or centuries.

  • $\begingroup$ I don't think collecting drinking water would be any problem, i remind you it was raining all the time, and he could reduce amount of food required for journey by taking baby animals. But it is just side comment $\endgroup$
    – user902383
    Commented Oct 20, 2015 at 15:16
  • $\begingroup$ @user902383 In the story it rains for 40 days and nights (at a ferocious pace, something like 10 meters of rain per hour, on average) but it doesn't say anything about the weather beyond then until the bit at the end when there's a rainbow. Good point about the baby animals. Limiting the story to land vertebrates makes the physical act of putting them all on a single vessel possible, and babies makes it substantially easier. $\endgroup$ Commented Oct 22, 2015 at 1:44
  • $\begingroup$ You've got enough space for the animals, barely, but you've left out 2 significant problems which the Bible didn't deal with, perhaps because it was thought that everyone would have known how to deal with them. First, all that eating and drinking would have led to a huge amount of animal excrement to be gotten rid of every day, every single day, and there were only 2 dung beetles. So there must have been some provision for bulky equipment. Second, the animals needed many different environments - and lots of bedding straw. Where was that stored? $\endgroup$
    – frank
    Commented May 17, 2016 at 2:31
  • $\begingroup$ Beetles are 'clean' so seven pairs of dung beetles rather than one pair. Not that that makes much difference. $\endgroup$ Commented May 18, 2016 at 9:43
  • $\begingroup$ @PeteKirkham Indeed, there's not really much point in looking at the realism of the story at all, but given the basic premise (moving all vertebrate species into a single floating container) it's more or less answerable. It's always going to require magic though. $\endgroup$ Commented May 19, 2016 at 21:55

It looks like you've gotten a few pretty good answers already, but I would just like to add a few things for clarification.

  1. Just in case you're picturing the Ark as a huge sailboat, keep in mind that the word "Ark", especially in the context of the Hebrew Bible, means something more along the lines of "coffin" or "box". So basically God told Noah to build himself a huge coffin for all the animals on the earth.

  2. God presumably took care of the herding of all the animals to Noah, leaving him and his descendants to worry about the actual building and not the gathering of the animals. They all "came" to the ark of their own volition; no one had to actually go out and gather them.

  3. I know someone already mentioned this, but according to the Bible, Noah had a life of 950 years and his children lived extended lives also. This would have made a hundred years constructing the ark totally doable, if not completely enjoyable.

I hope this helps!

  • $\begingroup$ I know what an ark is but thanks you for pointing it out to others $\endgroup$
    – TrEs-2b
    Commented Oct 20, 2015 at 20:06

If as suggested, it was going to take in the neighborhood of 100 years to build then it would make more sense for Noah to herd the animals together and walk them to the nearest mountain. He could then build a Hollywood-set type of boat and hope that God wouldn't look too closely.

  • $\begingroup$ Can't see a problem with hiding from Noah's flood on top of a mountain... $\endgroup$
    – NPSF3000
    Commented Oct 21, 2015 at 8:06

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