Jack Vance's The Blue World is about low-tech descendants of castaways on a planet that, as far as they know, has no dry land. (They live on giant lily pads.) What kinds of evidence should convince them that there is land somewhere?

  • Dust in the wind (Gobi dust crosses the Pacific), or smoke of a forest fire
  • Floating carcass of an animal clearly adapted to running on land

What else?


closed as too broad by Aify, James, Skye, TrEs-2b, JDługosz Oct 1 '16 at 10:41

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  • $\begingroup$ Would appreciate a few more details, for folks like me who've not read the book. How low-tech are we talking here? Are there known animals that live on land, or are they mostly land-free? What about the people? Anyways, like the question! :D $\endgroup$ – Atlas the Worldbuilder Oct 1 '16 at 6:07

If you ever find yourself lost at sea or in a watery world and you want to find land, the following tips may be helpful:

  • Deep water is dark green or dark blue. Lighter color indicates shallow water, which may mean land is near.
    • Vegetation or wood floating might indicate proximity of land.
    • Birds are usually more abundant near land than over the open sea. The direction from which flocks fly at dawn and to which they fly at dusk may indicate the direction of land. During the day, birds are searching for food and the direction of flight has no significance unless there is a storm approaching.
    • Presence of birds in the horizon usually indicates proximity of land. Wind generally blows toward land during the day and toward sea at night.
    • Shallow water is clear (in tropics). It might indicate proximity of land. In the tropics, a greenish tint in the sky is often caused by
      the reflection of sunlight from the shallow lagoons or shelves of
      coral reefs.
    • A fixed cumulus cloud in a clear sky, or in a sky where all other clouds are moving, often hovers over or slightly downwind from an
      island. (cumulus cloud: see image below)
    • In the arctic, ice fields or snow-covered land are often indicated by light-colored reflections on clouds, quite different from the darkish gray reflection caused by open water.
    • Clouds often gather themselves over corals islands and reefs. A change of pattern in the swell might indicate a change of tide around an island.
    • If the swell is decreasing but the wind remains constant, it indicates an island windward (which is protecting the sea).
    • In fog, mist, rain, or at night, when drifting past a nearby shore, land may be detected by characteristic odors and sounds. The musty
      odor of mangrove swamps and mudflats and the smell of burning wood
      carries a long way. The roar of surf is heard long before the surf is seen. Continued cries of sea birds from one direction indicate their
      roosting place on nearby land.
    • Land may be detected by the pattern of the waves, which are refracted as they approach land.

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Source: Getting to Shore at Sea


FYI: I am not a survivalist. The closest I've been to water is on a beach, both an oceanic one and on a riverbank fishing one time. If you find yourself in this situation, do not rely on the methods I suggest.


You nailed two of the big ones right off the bat: dust/smoke and biological debris. But there's several other things one could use to infer the presence of dry land.

Plate Tectonics
All that was stated about the locals is that they are low-tech and live on lily pads. Having not read the book (and partly from the vagueness of the terms you used), I have no idea just how low that low-tech is, but assuming they're able to swim and have been living here for some time, they're bound to find areas where the sea bed seems to slope upwards, either gradually or sharply.
If they can follow the slope upwards, then (theoretically) they should be able to at least find a sea mount, which is fairly close.

Coastal Life Forms?
If there are lily pads, then they must've come from somewhere! And if there is dry land, then there will be creatures adapted to take advantage of the halfway lifestyle. Birds, for example, cannot live forever on the wing; they need roosting places, to rest and nest. Creatures with limbs can't swim as efficiently as finned or flippered swimmers, but they can crawl on land.
So seek out life forms which are known to live at least partly on land, and follow them. They'll lead you to land.

Assuming the locals are native to the planet (I.e., evolved there), then they'll probably have stories about how they used to live on land. Such tales, whether oral or written, can be used alongside education to search for real-life places. The City of Troy, for instance, was a real city discovered by following clues left in the Illiad and the Odyssey. Such reverse-engineered maps could also lead to forgotten islands and the like.

Just some ideas to consider. Hope it helps!


When current hits a rock, a calm area surrounded by two branches is created on the lee side, with eddies from the left side flowing clockwise and eddies from the right side flowing counterclockwise. This would be interesting if the people were to reason by analogy from smaller example of this phenomenon to reason that a large landmass must exist because if it were not a landmass but rather say a floating lily pad, it would have been pushed to them. Another interesting example is clouds and precipitation or its lack. Or wind. But this would be harder to do because there would be no easy analogy. Also smoke from a large fire or floating branches or trees.


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