The plane had settled upside down on the edge of the trench, its propellers dug deep in the gray sand. Strings of bubbles rose from the wings and windows. I felt the water grow colder as I went deeper, and now I could see crabs and jewfish moving quickly across the bottom and puffs of sand from the wings of stringray that undulated and glided like shadows down the sides of the trench.

I got down to the pilot's door, slipped the spare tank off my arm, and looked through the window. He stared back at me upside down, his blond hair waving in the current, his sightless green eyes like hard, watery marbles. A short, thick-bodied woman with long black hair was strapped into the seat next to him, and her arms floated back and forth in front of her face as though she were still trying to push away that terrible recognition that her life was about to end. I had seen drowning victims before, and their faces had had the same startled, poached expression as the faces of people I had seen killed by shell bursts in Vietnam. I just hoped that these two had not suffered long.

I was kicking up clouds of sand from the bottom, and in the murky green-yellow light I could barely see through the window of the back door. I held myself out flat, holding on to the door handle for balance, and pressed my mask to the window again. I could make out a big, dark man in a pink shirt with pockets and cloth loops all over it, and a woman next to him who had floated free from her seatbelt. She was squat, with a square, leathery face, like the woman in front, and her flowered dress floated up around her head. Then, just as my air went, I realised with a terrible quickening of my heart that somebody was alive in the cabin.

I could see her small, bare legs kicking like scissors, her head and mouth turned upward like a guppy's into an air pocket at the rear of the cabin.