Swimming With the Tide

English Channel Swim Tracking has released its 2025 map of English Channel swim attempts, charting the routes of all swimmers who have so far tried to cross from England to France this year.

The English Channel Swim Tracks 2025 visualization is very straightforward - just hundreds of line strings plotted on a single map. Unfortunately, the sheer volume of data makes it heavy to load - in fact, the map repeatedly crashes my laptop. However, despite this, the project is still extremely compelling, and I like it a lot. It has taught me something new, and in a way that only a mapped visualization could.

I had always assumed that swimmers crossing the English Channel took the shortest, straight-line route between the English and French coasts. One glance at the map was enough to disabuse me of that notion. As you can see, most swimmers set off in an easterly direction - almost as if heading toward the North Sea. Those who don’t tend to swim in a southwesterly direction, as though they were aiming for the Atlantic Ocean.

Swimmers rarely take a straight path across the English Channel because of the strong, shifting tides. The currents change direction roughly every six hours, so starting at the right moment is crucial. Many swimmers set off just before a tide shift, allowing the water to carry them in a generally westerly direction while minimizing sideways drift.

As the tide begins to change, swimmers adjust their course and gradually turn in a more south-easterly direction toward the French coast. This careful timing and navigation allow them to use the currents to their advantage, rather than fighting against them. The result is that the tracks often appear curved or counterintuitive on a map, with swimmers weaving in response to the tides rather than following the shortest straight line route between England and France.

The average time for an English Channel swim is typically between 10 and 16 hours (though conditions and swimmer speed can push this higher or lower). Because the tide shifts roughly every six hours, most swimmers experience at least two tidal changes during their crossing. This is why most tracks on the map show at least two major twists, as swimmers adjust their course to move with - rather than against - the tidal currents.