Tidal whisper

Every twelve hours (give or take), around forty-five minutes after the start of the ebb and in anything less than a moderate breeze, we hear the same sound. It lasts for half an hour or so, and its timbre changes depending on the height of the wave, the cycle of the tides (it's always more pronounced on a spring tide, when sun and moon are in conjunction or opposition and the volume of water passing through the sound is at its height) and no doubt many other subtle and unseen factors. But most commonly it's something like a whisper, or a rustling of leaves or, when the temperature drops sharply at the edge of dark, a long, cool, rushing sound - the tidal equivalent of a chill breeze.

Fifty yards from the end of the jetty, a swathe of water not wider than a small river turns dark and a little fractious, and if you find yourself rowing against the current, you have your work cut out.

In the small hours, if I can't sleep, I find this phenomenom deeply reassuring.