What two shoreline locations on the planet are the farthest apart, using only “on-water” transportation?
Let’s say we had no transportation of any kind, except on water. Oceans, seas, navigable rivers, etc. And let’s say there are no canals, and we can’t dig new ones, e.g. a trip from one coast of Panama to the other would necessitate a trip around South America. And disregard factors like ocean currents, etc. And you have to travel in the most direct route possible. I’m looking for simply raw, physical measurements.
What would be the longest voyage connecting two shoreline locations?
The longest great circle (direct) route over water is from a point near Karachi, Pakistan, down the east coast of Africa, through the Mozambique channel , south of Africa and S. America, then north west across the Pacific to a point in Russia near the Kamchatka Peninsula.
It depends on whether you can use the Northwest and Northeast Passages. That is, can you sail over the top of North America and Eurasia? If not, it may be something like Murmansk to Nome.
If you assume there is a blockage in the Northeast Passage, then it may well be something like, point A on the north coast of Russia, to point B on the north coast of Russia but slightly further along, on the other side of the ice blockage, which necessitates going “the long way round” the entire Eurasian/African landmass. (As the Suez Canal is discounted.)
I’m not sure where you’d end up, but I suspect you might begin at Batumi, on the coast in Georgia. You’d have to sail through the Black Sea and the Med to Gibralter before even starting, really…
The OP mentioned navigable rivers, then specified shoreline locations. If you drop the shoreline limitation, or count the shores of rivers, then back 100 or so years ago, a voyage from Pittsburgh, Pennsylvania, to Bourke, New South Wales, would have been pretty long. (But I don’t think it can be done now, because the Murray-Darling is no longer navigable).
Including rivers, I’d change my starting point from the shores of the Black Sea to 1400 miles up the Danube! That’s quite a head start by the time it enters the Black Sea, although it is closer to the Bosphorus…
I was going to use rivers. They have a shore line all along them. I was thinking adding in two extensive river systems should extend the mileage a lot. Then with the rules changing it will become a some that can handle a cruise ship all the way. No mention has been given about the ability to switch ships like they would have at towns in the 1800’s, but traveling by water the whole way.
There’s one difficulty: The length of a shoreline isn’t a fixed dimension, it has a fractal dimension between 1 and 2. The distance actually depends on the scale of measurement! How Long Is the Coast of Britain? (Wikipedia)
Interestingly, “most direct” does not equal “shortest” in this case. Following the “most direct route” around a shoreline, by definition, implies that you’ll be closely hugging the convex parts of the coast. Depending on how closely, the covered distance may become infinitely long. Theoretically. (The other extreme would be the “straightest” route, that is, the longest great circle distance between two farthest land points. In other words the most remote island.)
Of course, a real ship would take some sort of “rounded off” route around the coast, essentially taking a shortcut. However, taking shortcuts is contrary to our objective of finding the “longest” distance.
The condition on the shape of the route has to be relaxed somehow to set an arbitrary upper limit. Like “always keep away at least 6 miles from the coast” (we’d need another definition for rivers).
I would say you have to look up the official length of rivers and then use straight line distances in the oceans avoiding land obstacles. This is of course not how a real voyage would run, but it’s the closest you can probably manage.
Yes I considered that the concave segments get replaced by straight lines, but for the parts that stick out you still have pretty much no choice but to sail around. Thinking about it, actually I’ve no idea if an exclusively straight and convex curve (that is, if you pull a rubberband around a fractal) can still be a fractal. Possibly not, if so, nevermind.
I still say though that one cannot avoid having to deal with the chaotic fractal character of maps. This problem clearly isn’t one that can be solved in a top-down approach, that is, by starting with a rough globe and then branching into detail. The first thing we’ll need to do for a definite answer is to map out every point in the world where your ship is allowed to be and where not, down to the width of the smallest boat. Otherwise you may get a totally different solution if you use a map of another scale. Add some mangrove swamps further inland or a long and narrow fjord that usually nobody bothers to put on maps, and you’ll easily be off by hundreds of miles and could use a different route altogether.