The shortest distance from the UK to Frances is about 21 miles as the crow flies. Nearer 28 miles for a swimmer, because of the strong tidal currents.
This image shows a GPS plot of one of the swims that I observed.
The water is never warm and sometimes very cold. 17°C (62.5°F) is about the warmest it gets. To add to swimmers' problems this is also one of the busiest stretches of water in the world. Up to 500 ships pass through the Straits of Dover every 24 hours. The Ship AIS web site is a brilliant way to see just how busy it is.
The rules of the CSA prohibit anything but the most basic swimming costume and cap, no bouyancy aids and no protection from the cold except for a layer of grease. Some swimmers even forgo this basic protection.
