He sighed heavily and swooned backwards into the water, touching bottom, opening his eyes to feel the sting of salt and watch the blurred sunlight for a moment before rising to his feet, satisfyingly wet all over. He shook his hair out of his eyes and then waded after Madhusree. The water reached his own ribs before he caught up with her; he eased himself down and started swimming beside her.

‘Are you all right?’

She didn’t deign to reply, merely frowning at the implied insult.

‘Don’t go too far.’ When they were alone, the rule was that Prabir had to be able to stand in the water. This was slightly galling, but the prospect of trying to tow a struggling, screaming Madhusree back to safety was something he could live without.

Prabir had left his face mask behind, but he could still see through the water quite clearly with his head above the surface. When he paused to let the froth and turbulence he was making subside, he could almost count grains of sand on the bottom. The reef was still a hundred metres ahead, but there were dark-purple starfish beneath him, sponges, lone anemones clinging to fragments of coral. He spotted a conical yellow-and-brown shell as big as his fist, and dived for a closer look. In the water everything blurred again, and he almost had to touch bottom with his face to see that the shell was inhabited. He blew bubbles at the pale mollusc inside; when it cowered away from him he retreated sheepishly, walking a few steps backwards on his hands before righting himself. His nostrils were full of sea water; he emptied them noisily, then pressed his tongue against his stinging palate. It felt as if he’d had a tube rammed down his nose.

Madhusree was twenty metres ahead of him. ‘Hey!’ He fought down his alarm; the last thing he wanted to do was panic her. He swam after her with long, slow strokes, reaching her quickly enough, and calming himself. ‘Want to turn back now, Maddy?’