‘About what?’

‘What do you think? I’ve been trying to get it out of you all night.’

Tom needs a long moment to realise what he is talking about. ‘One thing for sure,’ he finally says, ‘I’m not going to die a fucking virgin.’

‘A fucking virgin?’ Kenny says, and Tom manages a small laugh.

‘It’s easing,’ he says. ‘Oh, fuck, thank Christ. It’s easing.’ He laughs again, more loudly, a mixture of relief and embarrassment. His tone is forced and hearty, covering its recent tracks. ‘We’ll try again. You do the jumping.’

‘I think we should save our energy.’

‘Then crack another joke. It was the joke that did the trick.’

Laughter on demand proves impossible; all the jokes Kenny has ever heard seem to have done a moonlight flit from his mind, untraceably. ‘I could sing a song,’ he says.

‘What song?’

‘Any song. “Baa, Baa Black Sheep”. “ Twinkle, Twinkle Little Star”.’

‘The other leg’s cramping.’ Tom’s voice is edgy with panic again. ‘Jesus – think of something. You’re the brains of this outfit.’

For the first time Kenny wonders if he might be close to cramp himself. He shoves the thought from his mind. Old voodoo habits: to think a fear is to make it real, to conjure it up. Then suddenly he is too busy for such thoughts; Tom has rolled onto his belly and is clawing at him again, pushing him under.

‘We’re going to drown. We’re going to fucking drown!’

A stray finger pokes Kenny’s eye; he insinctively twists free and kicks away a metre.

‘Where are you? Oh, Jesus – you giving up on me?’

‘Just letting go for a few seconds. I need to piss.’

‘Piss here. You’ve got to hold me.’ Tom’s plea is gurgled through a swallowed mouthful of water, but Kenny kicks further away into the darkness. A horror story from the paper some weeks before comes back to him: of a married couple who hit a reef somewhere out among the islands and took to the water in life-jackets. The woman had been injured in the collision; after a few hours in the water, sharks began to nibble at her torn legs. Reef sharks, not quite big enough to end it quickly, but big enough to tear off small mouthfuls: toes, fingers, chunks of calf and thigh.

Knowing she could not survive, the woman had told her husband to swim away. And he had swum away, into the night, his wife lost to him, being eaten alive, her cries chasing him through the darkness.

‘Help me, Jesus, Kenny – help me!’

Kenny silently eases his head beneath the surface of the water, croc-fashion, and kicks further away from his friend. He surfaces some distance off, but senses that Tom might still locate him.

‘Help me! Help! . . . Help me!’ The gurgled cries carom between the high walls, amplified terribly. Even more terrible is the short silence that follows.

‘I’ll help if you don’t fucking panic!’ Kenny shouts. ‘I’ll help if you shut the fuck up!’