At Samphire Beach, a Japanese woman stands in front of Dover's white cliffs. It is 10 past seven on a Tuesday morning. Most people will be having breakfast or getting ready for a day at the office. Miyuki Fijita is swimming to France.
Through my aircraft window, the river resembled a snaking green lava flow. A couple of days later Iâ€™m swimming in it, a wetsuit protecting me from the 13C chill.
That there were once 300 of these quasi-socialist experiments in public leisure, and that there remain fewer than a hundred, reveals much about how our municipal culture has changed.
It is hard to list all the adversaries that the American long-distance swimmer Lynne Cox has overcome. In the past 30 years, this real-life mermaid has battled sharks, icebergs, the KGB and the FBI, eight-foot waves, ten-knot currents and impenetrable fog.
Two new books with almost identical titles illustrate the rise of a new literary phenomenon - the wild swimming tome.
In the haze of rubbed out chalk I can just make out: "Today's temperature 12C, 53F". The atmosphere is Dunkirkian among the old campaigners, some of whom are in their eighties.
The indoor pool was a child of the industrial revolution: mass construction began only after the Baths and Wash Houses Act of 1846.
It takes 114 strokes of front crawl to swim from one end to the other.
Columnist Matthew Parris has been called "ignorant" and his actions "dangerous" after swimming across London's River Thames. But up and down the country, people are dipping a toe in the trend for outdoor swimming.
I am swimming in the middle of the strait dividing Europe from Asia Minor and I sense most of us are not going to make it.