I am not going to tell you where I am writing about. It is one of those places of personal sanctity that has, miraculously, escaped the popular attention I am fully aware it deserves. Even avowed outdoor evangelists should be allowed to keep one or two of these places to ourselves.

I discovered it a few years ago, but had not gone back since. On a searing day this spring, after two excruciating hours inching through Manchester traffic, it flashed back into my head on my journey over the Pennines. Craving the mini-rebirth of a soak in wild water, I fled my car and marched up to it in my work clothes. There it shone, almost landscaped in its perfection, the porter-coloured beck tumbling down in bright cascades over exquisite water-smoothed shelves of rock. The cool pool at the bottom was treacle-dark and deep enough for submersion; water from heaven.

This oasis is not, of course, a complete secret. Reading Clarion Call: Sheffield’s Access Pioneers (recently published by the South Yorkshire and North East Derbyshire Ramblers), I found the pool had been a nude bathing stop-off on one of the walks led a century ago by GHB Ward, founder of the working-class Clarion Ramblers club and an imperious leading figure in the early access movement.

Of the book’s many wonderful pictures, one stands out: Ward skinny dipping in another pool, on nearby Bleaklow, some time in the 1900s – a statement more subtle than a mass trespass but progressive in its own way. As Ward, a socialist, wrote, “Many ills and rheums … accumulate largely because men do not know how to throw them off in the abandon with nature.”

I have returned to “my” pool several times over this summer. On the most recent occasion I took a few nervous glances around beforehand, then followed Ward’s example. The water felt like liquid silk, and was breathlessly rejuvenating. There was a jungle-green overhang of shale grit above the pool, and as I swam the sun glitter in the water made ripples of light dance over the ferns and moss; a touch of tropical lightness in the heart of the Dark Peak.