Shelly slashed at the net below the turtle, terrified that one of them would become entangled and the nightmare of her past repeat itself. The turtle stopped struggling, whether dying from lack of oxygen or sensing they were helping it, she couldn’t know. Seconds ticked by, their tanks becoming more depleted. Shelly willed herself to stay calm, to slow her heartbeat, to save oxygen. They had to have enough air to rise slowly. Finally, the last strands of polymer broke away and keeping hold of the turtle, they hauled it between them as they started their slow ascent.

Keeping one eye on the time she clipped herself to a loop in the shot line and hung there for her decompression. Harry came alongside, and they both worked on cutting away more of the punishing net from the turtle’s flipper. All the time, she hoped the turtle had enough air to hold on a while longer. Harry clung on to the front of the shell. Everything depended on the turtle not making a race for the surface to breathe. If it did, they would have to let it go or suffer the fatal bends.

Her blood boiled. How could fishermen be so careless? Why couldn’t manufacturers go back to using cotton, hemp, or wool nets? At least those materials would eventually rot away. The net they were cutting off the turtle may have been hanging off that shipwreck for over half a century, and killed countless marine mammals in the most horrible way.

The dive apparatus impeded an urge to scream angrily, as loud and hard as she could. She diverted her thoughts and concentrated on drawing the last nylon filaments from the creature’s wounded flipper. After swapping places with Harry, she started freeing its head. Cautiously, she looked into the turtle’s eye. One snap from that powerful beak could cut through her airpipe, which would certainly kill her.

As the last clump of net came away, Shelly gave the turtle one last look deep into its eye, made the OK sign to Harry, and gave the enormous carapace a gentle shove towards the surface. Great joy blossomed in her chest. Harry reached for her hand and together they watched the turtle’s silhouette rise through the lighter water above, pale turquoise light bouncing off the dark amber shell. Shelly was overcome by euphoria, made more intense because she couldn’t smile with an air-hose gripped between her teeth. Her elation was not just because the pressure against her dive suit had lessened, or because the turtle now swam free, but because she had realised the truth of the situation and come to terms with her nightmare.