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On an earth-like world I am creating there is a small island that is regularly covered in dense fog. The fog is thick enough that your standard human cannot see where the nearest mainland shore is.

Without visual cues is there a way to determine where the nearest shore would be? I need a logical explanation why a person would decide (intentionally) to go a particular direction given that visibility is really bad.

Limitations

  • Waiting for the fog to clear is not an options due to time constraints
  • Modern Era but no technology available
  • The mainland is approx 400 M away from the island
  • The nearest stretch of mainland is uninhabited
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  • $\begingroup$ I really appreciate your questions. The island is circa 400 metres far from the mainland. It isn't big, just one cabin on it and some land. The story is set in the current era. The mainland is populated but the neariest person is a few kilometers far. $\endgroup$
    – skornos
    Commented Mar 7, 2016 at 20:02
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    $\begingroup$ Welcome to the site, skomos. Can you identify how this pertains to worldbuilding, as opposed to, say, outdoorsmanship, or how this isn't purely character- or plot-centric? $\endgroup$
    – Frostfyre
    Commented Mar 7, 2016 at 21:58
  • $\begingroup$ I was going through all the stack exchange sites and posted this question originally at outdoorsmanship but they redirected me from there to this site. So I feel like being tossed like a hot potato from one site to the other one :D $\endgroup$
    – skornos
    Commented Mar 8, 2016 at 8:15
  • $\begingroup$ @skornos It's worth pointing out that just because a question could go to another exchange, that doesn't mean it couldn't belong here too. I think what Frostfyre is mostly questioning is if it's about world building. In my opinion you are pretty close to an "on topic" question. The main reason it might not be is the "I have a character" part. If it was flipped around a little to be a question about the world: "What indicators are there to find land if I can't see the shore" or something. Thats probably not right yet either. People in chat can probably help word it better so it can be reopened. $\endgroup$
    – AndyD273
    Commented Mar 8, 2016 at 14:29
  • $\begingroup$ To clarify. Are you standing on an island and looking for the shore of that island. Or standing on the island and looking for the shore of the mainland? $\endgroup$
    – Tim B
    Commented Mar 8, 2016 at 15:40

6 Answers 6

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The wind/breeze. Depending on the time of day, breezes tend to go toward shore during the morning as land heats up faster, and toward the sea in the evening as the land cools down faster.

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  • $\begingroup$ was the downvote for being such a short answer? $\endgroup$
    – bowlturner
    Commented Mar 7, 2016 at 22:05
  • $\begingroup$ That's a dumb DV reason, IMO. Great point, and the one most people are likely to know. $\endgroup$
    – Josiah
    Commented Mar 8, 2016 at 0:37
  • $\begingroup$ Thanks for this answer, we had a feeling there is something like this but couldn't find the exact information. $\endgroup$
    – skornos
    Commented Mar 8, 2016 at 8:09
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    $\begingroup$ Just one thing worth mentioning: If it's foggy it's unlikely to be very windy as any significantly stiff breeze would blow away the fog $\endgroup$
    – Ieuan Stanley
    Commented Mar 8, 2016 at 15:10
  • $\begingroup$ Generally yes, but not always, and it could be a lighter breeze. $\endgroup$
    – bowlturner
    Commented Mar 8, 2016 at 15:13
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Honey bee triangulation.

Bee's have a forage range of around 4 miles. Once they have collected their load, they will generally fly in a straight line directly toward their hive. (this is a good way to find wild hives, by the way)

If the island isn't to far off shore, he could observe a bee gathering nectar, and then making a beeline across the water.
If he made several such observations he could triangulate the location of the hive, but even seeing a single bee fly off would let him know what direction shore was, and that it wasn't that far away either.

Generally, when looking for hives, people will glue a small bit of cotton or other light colored bit to the bee while it is distracted foraging to make it easier to see as it flies away.

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    $\begingroup$ This is an interesting one $\endgroup$
    – James
    Commented Mar 7, 2016 at 20:19
  • $\begingroup$ no idea where you get this kind of knowledge but it sounds really interesting. Thanks :) $\endgroup$
    – skornos
    Commented Mar 7, 2016 at 20:39
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    $\begingroup$ @skornos I read entirely to much random stuff, but I'm not sorry about it. :) $\endgroup$
    – AndyD273
    Commented Mar 7, 2016 at 20:57
  • $\begingroup$ @AndyD273 haha good comment, I hope you don't mind that I will use it in the novel $\endgroup$
    – skornos
    Commented Mar 7, 2016 at 21:19
  • $\begingroup$ @skornos That's kind of the point of asking questions here :) $\endgroup$
    – AndyD273
    Commented Mar 7, 2016 at 21:33
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I've canoed on lakes with heavy fog. Maintaining a straight course requires a compass (easiest) or long piece of cord and a float. (By streaming it behind you and keeping the wake of the float centered in the wake of the boat, you can keep a straighter course.

Conditions that produce fog often have a layer of cold air near the surface. Since the speed of sound is slower in cold air, sound tends to refract toward the surface -- sounds carry much further.

So some form of sonar may work. Construct the equivalent of the clap board used for syncing sound and action on movie sets. The idea is to make a single sharp sound that is uniform.

If you have two people, one person can construct ear funnels out of bark to make hearing more acute and more directional.

If there is any surf running at all -- even light swells -- these are generally going to run toward the main shore -- within the 180 degree angle of the mainland. This assumes a linear mainland with a sloped beach. Such a beach can't act as a source of waves. Cliffs however can reflect waves.

Waves hitting the shore may make enough noise to be heard from a distance, especially with treebark sound amplifiers.

Because strong waves can't come from the mainland side, you may find that there is a difference in the evidence of wave action on different parts of the island. I would expect the dominant signs to be in the direction of the dominant winds for your location. Things to look for: Driftwood, seaweed further up the beach, larger sand grain/rocks (bigger waves move bigger stuff)

If you know what direction the land is, but don't know where that direction lies, you may be able to tell at sunrise or sunset. (That is, you know that the land is East of you, but which way is East?) Unless the fog is extroidinarily thick, you may be able to see a general lightness in one direction. If it gets brighter, as it fades in directionality you 've seen sunrise.

When fog is dense it is frequently in thin layers. Depending on the shape and vegetation of your island, you may be able to climb high enough to see.

If you know the local currents and tides, you may be able to pick up their directionality by running floats on cords from the island. Unraveling your sweater is a source of cord. E.g. You know that the rising tide has currents from the Southwest. You can tell if it's rising by putting markers on the beach.

If the tides have a significant rise and fall, your 400 m to the beach can be far less at low tide. E.g. In the Georgia Straight between Vancouver Island and the coast of BC tides run 30 feet. At a 1 in 10 slope, that chops 300 feet off of each end of your journey. Your 400m is now 200m. Maybe now you can hear the waves lapping.

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Unless your island is dead-flat, then 'downhill' is likely to lead you to the shore - particularly if its a small island.
Determining which way is downhill could be tricky if it's close to flat though and a large island with valleys & craters would complicate things ...

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  • $\begingroup$ He's looking for the shore of the nearest mainland/other island...not the shore of the island he is standing on... $\endgroup$
    – Tim B
    Commented Mar 8, 2016 at 15:22
  • $\begingroup$ @TimB - that wasn't specified in the original question. It's been substantially edited since then (and not by the OP, so someone has completely changed the context of the question without any confirmation from the OP that this reflects his requirements) $\endgroup$
    – brhans
    Commented Mar 8, 2016 at 15:26
  • $\begingroup$ The edits were taking extra information left in the comments by the OP and putting them into the question. However you are right, the original question was vague and this was a potentially valid answer to it as it stood then. $\endgroup$
    – Tim B
    Commented Mar 8, 2016 at 15:28
  • $\begingroup$ @TimB The OP's reference to the mainland was in reply to someone who asked how far away it is. He never specified that it is the mainland shore he's looking for and his description of the fog (thick enough that your standard human cannot see where the nearest shore is) leads me to believe that its the island shore he's looking for as it wouldn't take particularly think fog to obscure the mainland from the island. $\endgroup$
    – brhans
    Commented Mar 8, 2016 at 15:35
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Use the environment around you to lead you to it.

Sand

Since shores are eroded, look at the earth beneath you and see if you can notice patterns such as increasing amounts of sand - quartz (silicon dioxide) and feldspar (sodium, calcium, and silica), which are in abundance near beaches, and increasing amounts of pebbles/worn down rock.

Some islands are made out of volcanic material, so increasing amounts of black sand (basalt) are also indicative of an oncoming island perimeter,

Elevation

Shores to be on a lower elevation, so if you see decreasing elevation, going downhill for a while would likely bring you to the shore.

Rivers

Rivers will also find their way to the shore, so if you see a river, follow it to the delta. However, a caveat - not all rivers will end at a large body of water. However, all rivers flow downhill, which is helpful since the shore will likely be at a lower elevation.

Animals

Some animals are just better at finding water, due to the raised humidity, the sound, the scents, etc. Other times, animals that have found water might signal to other animals that water is present. If you can identify those animals, you can follow them.

You can also use your own sense of smell. Saltwater can have a very strong scent, and you could use the wind to track where the scent is coming from. Another chemical, geosmin, is responsible for that pleasant earthly scent (petrichor) when the earth is disturbed by water. Humans are very sensitive to that smell (can detect it at as low as 5 parts per trillion).

Even if the ocean water doesn't cause that scent, rain does, and it rains more near coastal regions and where the wind hits high elevations from the ocean side.

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    $\begingroup$ OP has rendered my answer useless making it so you're looking for a mainland shore instead. This answer only applies to the original question. There are some terrain indicators looking at a shore from the outside (Sandbars, troughs, etc) but the fog makes it useless and they're usually close by to the shore anyway. $\endgroup$
    – The Anathema
    Commented Mar 8, 2016 at 15:59
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Sound?

Several "If's" follow, but it might work...

If the nearest shore is about 400m away then the round trip time for sound from the island will be about 2.3s.

If the not nearest shores are, say, 500m away, that will add over 0.5s to the round trip time, which enough of a difference for a human to perceive.

If the nearest shore has any feature that will echo sounds, making a loud enough noise to carry back and forth over 400m of calm water is possible.

The islander would not be able to find the exact point that is closest, but he or she could be in the ball park.

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