Stefano crouched on the sharp volcanic rocks. Below him in the shade-dark water a sea urchin tipped back and forth in the rising swell, precisely as it had a million years before. Stefano looked at the sole of his foot. The broken spines were thin and black below the reddened skin.

He looked out. The wind from the north whipped the sea into low white-flecked waves closely lined together, like hard-packed sand at low tide. The inflatable mattress was moving fast.

His diving knife was strapped to his calf as always. He thought of things that should never happen and dived into the water. The first bodylength down was summer warm; when he hit the cold from the underwater springs he arched his back and arrowed through the bubbles to the surface. The mattress was further out and further down the channel, still red he knew but black against the heat-white horizon.

The sun worshippers on the rocks around him did not see his dive raise a trail of spray. Only the girl rolling a herbal cigarette saw the knife. She reached for her phone.

The wavelets smacked his face as he swam overarm towards the mattress and the shape lying motionless on it. The water whipping off the crests of the waves felt like sand in a desert storm. He realised his habit was to turn his head to the left to breathe. Now into the wind. He had left his goggles on the rocks. But he never swam without his knife.

The mattress was closer now, drifting fast. The form on it had not stirred. He turned on his back to rest a little. His knife was still there. He touched its handle, cold in the cold water. One last effort.

He breathed in deeply and ploughed on, shoulders stretching. The only cloud in the sky passed across the sun and the sudden shade woke him from his effort. Arms and lungs burning he arrived at the mattress as the wind whipped the waves higher. He held on with one hand and felt himself being pulled through the water, out towards the open sea.

He thought.

With a single strike, he slashed the mattress with his knife. It folded, crumpled and disappeared below them. Now the wind and waves would not take them so easily.

The girl speaking on the phone shaded her eyes with her hand and saw the two black dots in the blue. One disappeared, then the other, then both reappeared. They were moving slowly towards the coast but faster along it. She lost view of them around a high outcrop and closed the phone call. ‘Too late,’ she whispered. ‘Too late.’