As the teams dispersed – the divers to their clubhouse to gear up, the Defence boys returning to their boat – I caught Bram’s arm. ‘Is this really a good idea?’ I said, low enough that I hoped nobody else could hear us. ‘Why not just let them go? Give them the coordinates of the site. Why do we have to be involved at all?’

‘Jo, I know you care deeply about what you do. So you’ll understand what I mean when I say that site is ours. It’s in our waters. We discovered it first! If we don’t go along and protect it, what purpose do we serve? How is that helping Texel? The people around here rely on us to protect our culture.’ Seeing my anxious face, he patted my arm reassuringly. ‘Don’t worry. We’ll behave ourselves, as long as they do. Come on. Let’s get you suited up.’

He led me through the clubhouse to the wet room, a caged area housed outside the main building where the divers washed and dried their gear after every use. Fluoro buckets brimmed with weight vests, glass snorkels and plastic fins. Wetsuits crowded a clothes rack, nestled tightly together like animal pelts. I chose one that looked about the right fit and selected a mask from a tub, my world shrinking to the narrow vision glimpsed through the tempered glass lens.

‘Stick close to me,’ Nico said. ‘The visibility should be pretty good today, but there are patches – especially if we end up under the bow – where it gets a little murky. I’ll make sure you have a torch.’

He turned to help Cristof strap on his tank. The older man was encased in a blue wetsuit edged with bright pink flames along the arms and legs. ‘Flora chose it,’ he told me. ‘She thought it might help in the event of an accident. You can’t miss me, she said.’ He tapped the dive computer strapped to his wrist. ‘Anniversary gift. Flora insisted on buying the best model around. You can set it in your sleep – but of course, Nico’s the expert navigator.’

When everyone was ready, Bram led us outside and performed the final checks on the group’s equipment.