Before he could act, a blow like a kick from a carthorse propelled him into the cavity and slammed him into the far end. His first thought was a crocodile, but then a stinging blast across his back told him it was Boerman’s water jet.

In the ensuing tumult, his fins were blown off his feet. Nash clamped his hands over his full-face mask as he began to rotate horizontally. In mounting terror, he realised each revolution was driving him deeper into the packed mud. The power of the jet was impossible to resist. He felt his air hose coiling around him, locking his arms against his chest. When it snapped, his next breath was liquid mud.

Abruptly the jet stopped. The yammering of the pumps was gone.

The overwhelming sensation was of tremendous compression, and it took him a few seconds to understand the full horror of his predicament. He was wedged beneath the hull of the Albany like a doorstop, unable to use his arms, hands or legs for leverage. Only his feet could move, and they were uselessly treading slop.

The old Nash would have methodically tried to untangle himself, conserving every drop of oxygen in his tissues. Now he reacted like a wild animal in a snare, thrashing and twisting as panic consumed him. The fury of his struggles intensified with each passing second.

But somehow a hand, then an arm, came free. Grabbing the coils of air hose, he ripped them down his torso and freed his other arm.

With hands like talons, he dragged his trapped legs behind him, blindly groping for what he hoped was the way out. The only point of reference was the back of his head bouncing on the hull. He thought he saw a lighter shade of brown and made for it. The pain in his diaphragm was indescribable . . . a prelude to blacking out.

When Nash exploded from the gloop, he looked like a possessed creature from another world. In a gout of vomit and mud, he dimly heard himself screaming – a terrible wail that sent the birds in the forest chattering.

‘Put him down here, quickly!’ cried Singkepe, as many hands picked Nash up and deposited him on the deck. He could feel a rough finger inside his mouth, another scraping mud from his nostrils. For a moment, it was like drowning again, and he began to protest.

‘Let me through!’ He heard Mia’s voice. ‘Move!’ Her hands held the sides of his face. Then he was rolled on to his side. Something was put under his head. ‘It’s OK, it’s OK,’ she soothed him. ‘I’ve just got to make sure your airways are clear.’

He tried to open his eyes. The pain was excruciating, as if his eyeballs were set in cement.

‘I can’t see,’ he gasped.