I am thinking of a scenario in which a tunnel linking Hungary to Morocco is built around the 1500s by the King of Hungary in an attempt to colonize Morocco to get a border with the Atlantic ocean. What I am asking for is, could it be feasible in real life?

  • 1
    $\begingroup$ Is the tunnel in a straight line from one to the other? So then is the question about the engineering feasibility of a country from around the 1500s building a couple-thousand mile tunnel, crossing under a sea for a substantial length of it? $\endgroup$ Aug 16, 2022 at 19:33
  • $\begingroup$ @user535733's answer is great. As for feasibility of construction, that's already answered elsewhere. Spoilers: not feasible. $\endgroup$
    – jdunlop
    Aug 16, 2022 at 20:19
  • $\begingroup$ Can you edit your query so that you pick either a) "possible" or b) "feasible". They're not the same thing. $\endgroup$
    – elemtilas
    Aug 17, 2022 at 2:40
  • $\begingroup$ If besides this tunnel the rest of your story follows real history, they'd better hurry with the project and do it at the very beginning of the century. Hungary was indeed one of the great powers of Europe in the 15th century and the beginning of the 16th, but they got set back by a civil war in 1514 and then suffered such a blow from the Ottomans in 1526 that they never completely recovered from it even to this day. (hm, maybe all that great effort wasted into the construction of this tunnel led to their downfall? ;) ) $\endgroup$
    – vsz
    Aug 17, 2022 at 4:43
  • $\begingroup$ I voted to close this as a duplicate of that older question because it's intrinsically the same problem in the same time period with the same answer (I was considering simply duplicating my answer here... but that's the essence of a duplicate question). Note, however, that your title and your post ask two different questions. Is colonization through a tunnel possible? Of course. Can a 1,000+ mile tunnel be built in the 1500s in a reasonable time period for a king (or his grandchildren) to use it? No. $\endgroup$
    – JBH
    Aug 17, 2022 at 9:14

2 Answers 2


Only with magical assistance.

The shortest possible great-circle route from Hungary to Morocco is 2040km (1260mi).

An average reasonably-fit adult human can march about 35km each day on a long journey. Since we're assuming a roadway in this tunnel, let's be charitable and bump this up to 45km each day for each of the 45 days it will take them to traverse the tunnel.

In other words, each person traversing the tunnel must carry 45 days' supply of food, water, storage for their bodily wastes (they cannot leave it in the tunnel -- that would be disgusting!), and a source of light that won't asphyxiate them.

Let's see how much water that is: 4 liters per day means about 180 liters of water. For the average person in the 1500s, that's over three times their body weight. Of just water. That they must slog 45km every day. For a month and a half. And the weight doesn't decrease by too much, since they must carry their wastes back out of the tunnel!

Let's say folks get clever and pile their food and water on an oxcart. Same problem: The oxen need fodder and water too, and their cart cannot carry a 45-day supply for themselves, let alone any cargo.

So finally one of the King's advisers turns it into a rocket problem: Every couple hundred kilometers, the tunnel is widened into a tremendous supply depot. An army of oxcarts hauls cargo to the nearest (and hauls out the waste!), a smaller army forwards to the next, and so on, until a single colonist can stumble out the African end, barely alive and smelling utterly foul. If you do the math, you will conclude that the entire population (and all the oxen) of Hungary are inadequate to this task.

But it's all academic anyway. They don't have a source of light that does not involve combusting oxygen, so the miners building the tunnel will keep mysteriously dying of asphyxiation while still under their first mountain of the Alps.

  • 1
    $\begingroup$ +1 for addressing not the feasibility of the tunnel's construction (already addressed in a different question) but just the problems with traversing it. Very nice. $\endgroup$
    – jdunlop
    Aug 16, 2022 at 20:18
  • 1
    $\begingroup$ Great answer, however if the tunnel is almost perfectly level and well-paved then there is no reason that the people can't push their own supplies in carts rather than adding beasts of burden. Not that it helps much - they won't be able to make 45 km/day pushing a heavy cart all the way and they need domesticated animals at the other end to establish their colony. $\endgroup$ Aug 16, 2022 at 22:55
  • $\begingroup$ I'm not sure they need light. Do it with train carts (pushed, no engine) and each cart is "connected" to the one in front by poles suspended from ropes. Get too far from the one in front, the pole pulls forward, a noise maker touches the wheel. Get too far back, a different noisemaker touches. Unfortunately, they still asphyxiate, breathing alone will make it deadly. $\endgroup$ Aug 19, 2022 at 1:29
  • $\begingroup$ @LorenPechtel Oh, I'm pretty sure folks will want light so they can avoid stepping in all the human waste and other garbage left behind by tens of thousands of previous colonists who weren't diligent enough to clean it up and pack it out. And to step over the corpses of the colonists who died in the tunnel and maneuver around the endless stuck and broken carts, of course. $\endgroup$
    – user535733
    Aug 19, 2022 at 3:07
  • $\begingroup$ @user535733 Ouch on the breakdowns. I was figuring they would use chamber pots. $\endgroup$ Aug 19, 2022 at 17:52

Nah, it was more feasible to build two tunnels...

Another answer explains well why the Hungarians built two tunnels. One starts from a river at the surface and slopes ever downward, and one is very deep and slopes ever upward. The design allows water to fall from the high tunnel to the low tunnel at a vertical tunnel near the site of active excavation. These vertical tunnels are blocked off and replaced further on every year or so as the miners move out of range. The falling water turns the shaft of a primitive machine that bores out the rock, and men slide it onto rafts that they send out on the waters of the low tunnel. A constant stream of rafts arrives in the upper tunnel loaded with things for the workers and overseers: food, clothes, drill bits, opium, drabs ... everything a productive underground colony needs. But I hope you didn't need to finish your project by 2022. :)

The less said of the massive ever-turning slave-driven shaft that lifts all that excrement-laden transport water and sledges of excavated stone and garbage back up out of the abyss, the better. :)


Not the answer you're looking for? Browse other questions tagged .