It’s so hot at the moment that even the water isn’t empty. When I go to Herne Bay, I walk away from the main promenade, towards the theatre and the grassy cliffs, the Downs country park. I find a patch of empty shingle and get straight in the water.

Weed collects blackly along the shore line. To my right, a family play in an inflatable boat. The water is warm and I miss the chill of winter. Still, it is a relief to be in the sea after the relentless, though welcome, sunshine. The water is cloudy and grey, dipping up and down. As the waves push in they explode in white, then suck the shingle back with a jingling sound of stone knocking against stone.

Seabirds swoop down low over the water’s surface, then glide up into the open sky. The air smells of salt and barbecues, charred meat cooking, the off-green smell of the sea. Striped wind breakers line the beach. I am reminded of the “British Seaside” exhibition at the maritime museum, full of characters making a day of it at the coast.

While I miss the solitude, it’s nice to see everyone enjoying the beach. There’s a theatre just past where I swim and the queue snakes out of its doors. The queue next door for ice cream is just as long.

I sit for a while at the edge of the water, where the foaming waves rock me and the sound is loudest. After I dress, I walk up through the Downs country park, through long grass and butterflies, and look along the chalk coast to the ruined towers of Reculver castle at the end of the bay.

I’m raising money for the Alzheimer’s Society. Please sponsor me at http://www.justgiving.com/swimbonnieswim