Worldbuilding Stack Exchange is a question and answer site for writers/artists using science, geography and culture to construct imaginary worlds and settings. It only takes a minute to sign up.
Sign up to join this community
In order to account for an immense amount of technological and cultural disparity, I have been attempting to figure out ways that the world in a setting could be extremely hostile to travel. The idea I came up with was to have a planet that is majority-water with two moons that have extreme effects on the tides of the world, thus making sea travel (and even coastal living) an arduous task.
Tides are predictable.
The thing about predictable hazards is that they are less hazardous. If you know it is dangerously cold you can prepare for the cold. If you know there a fierce beasts you can come armed and in strength.
Tides are eminently predictable and seafarers have been using knowledge of tides for millenia. Super high tides would not make it more difficult to live on the coast because you would live above high tide, as people do. Super low tide would not make it hard to sail around because your boats would sit on the bottom and you would sit in the bar until the tide came in.
Until they aren't...
I am thinking of 2 moons in a stable orbit like Phobos and Deimos. But what if they weren't? What if 100 years before a new moon showed up. The old moon was thrown into an elliptical orbit. Now you have some adventure possible. The 2 moons are not in a stable orbit and are jockeying for position. High tides when both are closer are higher than anything in recorded history. Low tides expose the ocean floor for miles.
It would be very tough to predict what tides would do. That might work for your story. Plus if the arrival of the moon were historically recent the shock of unpredictable tides would impact society harder.
with how Willk says it there is little else to say, but one thing here is that you could get the moons in a type of twin orbit, but with a twist, one moon orbits the other sometimes, this could make the tides very, very high, or very very low, if the moons are at a sufficient distance you wont have to worry of the second moon crashing into your planet, and there are more variable key factors, such as the pull of the moons, their size, the gravity of your planet, the sun, the atmosphere gasses, and so much more, also another factor is the actual water, is oxygen diluted in it, is salt? etc.
edit: i forgot the size of the star, the type, the zone you are in farther or closer, and the actaul size of your planet : )
i know this is not the answer you were looking for, but i hpe this helps, also this would do great on the astronomy and physics stackexchanges also, for this kind of questions you need to add the hard science tag
