Open water is the hardest thing to draw

Everything that makes a route drawing legible is missing from a swim. There are no roads to follow, no junctions to turn at, no reason for the line to bend except that you did.

Which makes the good ones unusually honest.

What a swim track actually shows

Three things, and none of them are geography.

Whether you swim straight. Almost nobody does. Sighting every six strokes gives a line that scallops gently towards whichever side you breathe on, and the drawing shows it plainly. The first time people see their own crossing they usually laugh.

Where the current was. A crossing against a tide bows. The bow is not you being bad at swimming — it is the water moving under you, recorded.

Where you stopped. The small knots where you trod water to sight properly, or to work out whether the far buoy was the right buoy.

The GPS problem

Worth knowing before you expect too much: a watch on a wrist that spends most of its time under water gets a much worse fix than one on a handlebar. The track is noisier, the distance usually reads long, and short pool-style sessions in open water can come back as scribble.

Longer, steadier swims are far kinder. A crossing draws well. A forty-minute session of loops around a lake usually does not.

The one that works

A point-to-point crossing with a known start and a known finish is the swim that belongs on a wall. It has direction, it has a reason, and the wobble in the middle is the interesting part rather than a distraction. Print that one clean, with no map behind it — there is nothing on the water to show anyway, and the empty space is the subject.