Waterlines are a beautiful feature of western 19th-Century maps. They look like ripples radiating out from the coastline.

Waterlines on a map of The Isles of Scilly, Ordnance Survey, 1896. From National Library of Scotland.

Le Choléra, 1884. Carte du choléra en Europe / dressée par L. Carvin. From Bibliotheque Nationale de France.

Though they aren't the only way to draw water. The first of these notebooks collects together lots of examples of the different graphics used in maps of the past for water.

In Notebook II, I demonstrate drawing waterlines using JavaScript and D3.js.

I encounter some curiosities with smoothing functions:

And create some wilder versions:

Deforming waterlines with map projection

Notebooks III and IV cover making waterlines move like real water, by transitioning SVG paths:

Or generating image frames with HTML Canvas:

See the notebooks for the code, more visualisations, and thoughts and reflections about waterlining on maps—especially, which direction should waterlines move: inwards or outwards?