James hung there watching the fish until he decided to go deeper and see if there was anything bigger out there. He swam on, feeling tiny in this great blue void. He soon lost all sense of time and space and it was only when he heard the dull throb of an engine that he was brought back to reality.

He assumed it must be a fishing boat and realised that he might be in some danger out here on the open sea. He briefly put his head up to look around but could see nothing. He was amazed at how far he had swum, though: the shore looked miles away. He ought to head back. He felt suddenly cold and tired and, as he bobbed there in the water regaining his strength, the engine sound grew steadily louder and louder. Something was coming straight for him. But the goggles had steamed up and he was almost blind.

Where was it? Where was the boat?

He thrashed in the water, spinning left and right, but could see nothing.

The noise rose to a deafening scream and from out of nowhere a huge shadow swallowed him up. In his panic he dived down and looked up just in time to see what appeared to be the hull of a boat ploughing into the water above him, only inches away. It caused an almighty splash and an explosion of swirling bubbles. He felt a great boom and a thud and his body was hit by a shock wave. He tumbled through the depths, not knowing which way was up or down, tangled in a confusion of churning water. He swallowed a lungful of sea and wildly groped for the surface. Then at last the water stilled and he found his way up into fresh air and sunlight.

He floated there, treading water, choking and spluttering, wondering just what the hell had happened.

He tore the goggles off his face and was amazed to see a big white Sikorsky seaplane cruising through the waves and executing a long lazy turn. What he had thought was the hull of a boat was one of its two big floats, which were suspended in a complicated forest of struts below the wings. It coasted along under the power of its four propellers and finally came to a halt, its belly resting on the swell.

A double door at the front opened up and James saw a man in military uniform preparing a small dinghy.

James swam over for a closer look, but the dinghy was launched before he got there and he followed it on the long tiring slog towards the shore. It was too far away for him to see clearly who its occupants were but he could just make out the figures of a man and a woman sitting in the stern.