After hours on the road, the sea is calling. The sun is dark and evening is coming on and we are hot from walking along the path from Carbis bay. Porthminster is the first of St Ives’s bays we come to and we waste no time.

The waves foam in the break zone, but once past that, the muted turquoise water swells and falls and takes us up and down with it. Salt slips into my mouth and my body breathes again, stretching in the salt and the chill. Soon it doesn’t feel cold at all.

We stretch forward, arms pulling toward the horizon then along, parallel to shore. We let our feet sit on sand and we jump with each oncoming rush of water, rising up and above it and letting it defy gravity for us, just for that one surging moment.

The long car journey and the numbness of muscles too used to being cramped is gone. We are out at sea. Soon, we will dry off and dress and walk into the town. We will get fish and chips and eat them looking out over the harbour, ever watchful of crafty seagulls. We will walk out along the harbour arm and look back to see a seam of glorious pink hanging in the darkening sky above the houses. But for now, we are part of the sea, wet and salty and exhilarated. We kick, we splash, we swim.

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