Thursday, August 13, 2020

Mapping tutorial: Serpent Coast (part 1)

I need to make a map for an upcoming adventure, so I thought I'd share my drawing process with you here.  If you'd like to follow along, grab a pen, some paper, and a pencil for planning ahead.

The country we'll be mapping is called the Serpent Coast.  Here's what I know about it so far:

  • Deeply-indented coastline.
  • Lots of islands.
  • Mountains.
  • River flowing in from the southwest.

Let's head over to Google Maps for some inspiration.  This adventure is supposed to feel sort of American so I'll start with the American coast and wander around for just a few minutes.

Maine looks pretty good: plenty of inlets and islands on the coast.  Part of the Chesapeake has nicely-indented coastline, though it's not mountainous.  Puget Sound looks even closer with the mountains and the coastline.

But there's a portion of southeast Alaska where the Stikine River meets the sea and it's just about perfect.  The coast is deeply indented with fjords, there are plenty of islands, and there's even a river cutting its way through the mountains.

The goal isn't to copy this terrain exactly; we're just looking for inspiration.  Looking at Alaska helps me feel like I could imagine the Serpent Coast, and maybe even draw it.

Like most coastlines, this region is a bit of a fractal.  There's an overall shape broken up by inlets and channels, forming smaller shapes broken up by smaller inlets and channels, and so on down.

First we need to do some planning.  Some people like to use a pencil and erase all the planning later; I prefer to plan on one sheet, then lay another one on top to do the final artwork.  Either way works.


Let's start by sketching out a vague shape to enclose all the land.  (I'm actually drawing this in Photoshop, but with the same techniques I use on paper.)

Next we'll add some inlets to break up the land.  Inlets are (more or less) perpendicular to the coastline, and they're (more or less) much longer than they are wide.

Now we have a new coastline.  Adding smaller inlets works the same way, but remember that they're perpendicular to the new coastline -- we don't really care where the original line was.

Some of the inlets meet up inside the land, forming a channel, separating an island off of the main landmass.  It's starting to look a bit more like the Alaskan map we started with.  Let's do another round of inlet-carving and see what we get.

If these inlets are starting to look a bit like river networks, that's because they are.  (Not quite -- thanks to Linden for the correction.  Fjords are glacial valleys that have been drowned by rising seas.)

I think that's enough planning; time to draw the actual coastline.  If you have a thicker pen, I suggest using it here.  If not, a regular pen will do just fine.

Let's start with just one small part of the coastline to get a sense of how this works.  I'm going to trace over the planning lines (more or less), adding inlets and channels just like before, only smaller.

Like we saw with the Alaskan map, it's fractals all the way down.  Notice how there's nothing really special about this step -- I'm adding inlets and sub-inlets, just with a darker ink.  And don't worry about being precise.  Real coastlines are rough and random and variable.  Some parts are smoother, some are more jagged.

Next we'll draw the rest of the coastline the same way, then erase the planning lines.

I'm fairly happy with the results.  It looks a lot like the fjordlands of Alaska and it also reminds me of western Scotland.  There's something off about it, though.  Is it too uniformly-fjordy?  Actual coastline like this seems to have some asymmetry to it, based on the elevation of the terrain.

But I could keep editing this forever.  Like they say, creative projects are never really finished, only abandoned.  At some point I have to say it's good enough to ship or it won't get done at all.  So we're moving on to the next step.

Shore Treatment

Remember the first image I drew up top, with "land" on one side and "sea" written on the other?  Those labels were needed, because a plain line on a map doesn't really tell you which side is which.  We're going to add some wave lines around the shore to help distinguish land from sea.

Here's where your choice of media matters.  If you're drawing with ink on paper, come back to this part later, after you've labeled settlements and such around the coast.  You don't want the wave lines to cut through the labels.

For me, I'm going to draw the waves now.  Since I'm drawing in Photoshop, I can just hide any waves that interfere with the text later.

The waves should be an irregular broken outline, less prominent than the coastline.  I suggest using a thinner pen if you have one.  If not, use a light touch and add more gaps than what you see here.

It's nothing fancy, but it helps show which side is land and which is sea.  Here's how it looks with a second wave line, a little sparser than the first:

And with a third:

Zooming out to the entire map, you can see how the wave lines add texture and definition to the water.

That's probably a good stopping-point for today.  Next time we'll add some rivers, mountains, and symbols to the land.

Let me know in the comments what kind of map you'd like to see in future tutorials.

(Continue to part 2.)


  1. This looks great! Most fjords are flooded glacial valleys, not river valleys. That's why they're so deep.

    I love the wave lines for the shoreline. Do you drawn these by hand in Photoshop or do you have a brush that you use?

    1. Thanks! You're right about the fjords -- I'll add a note.

      The wave lines here are all drawn by hand in Photoshop. I'm trying for a very hand-drawn look for this series.

    2. By the way, if you wanted to draw wave lines like this in Photoshop in a more automated way, here's what I would do:

      1) Draw the coastline as a vector.
      2) Expand it some number of pixels.
      3) Trace the vector with a plain round brush with some size variance.
      4) Trace the vector again with an eraser with some size variance and scatter.

  2. Very useful! Thanks. How do you do rolling hills?

    1. I've got a region of rolling hills on the map from my last adventure: