‘Why not?’ Max asked. He shook his fist in the air. ‘This is how we show the fascists!’

By this point in the day, Max had lost some of that defiance. Goose-pimpling in the wind, he dumped his wallet, keys and phone.

‘This is an ocean,’ Damien said with appreciation, trying to console himself for the lack of surf. It was true, though: this was his idea of what a coast should be – wild and rocky, with strong currents. Forces beyond human control, with enough power to pummel you into insignificance. The Atlantic coast of Spain was nothing like the Med, which he thought of with disdain as a cut-rate paddling pool.

‘Like the beaches at home. Awesome natural beauty.’

‘Natural beauty, huh?’ Max grinned. ‘You’re digging it up out of the ground. A mine with a beach, isn’t that what people call Australia?’

Damien returned the grin. ‘We don’t mine everywhere,’ he said.

He felt defensive at the dig, but he wasn’t about to let Max see this. This early in the trip, they were still testing each other, re-establishing their dynamic. Max was affectionate, but also deeply competitive, going in for one-upmanship.

Later, Damien realised that they should have paid more heed to the movement of the water, but other things vied for their attention. For Max, it was the bridge out to the island with the old hermitage. He said the path was marked with the stations of the cross, probably for the use of villagers when they held processions. ‘But their faith has weakened!’ he declared, shaking his fist again, this time in mock-disapproval at the failings of Christendom in general.

For Damien, who knew something about geology, it was the dramatic striations in the causeway and the cliffs. These were shale bed deposits that ran seam-like through the rock, signs of the long-ago rift that had caused the continents to separate, allowing water to rush in and fill the breach. Waves had been pounding on the cliffs for millions of years since.

And for both of them, it was the shock of cold when they leapt in. It was even more intense than Damien expected, heart-thumpingly brisk. There was nothing you could do to prepare yourself for cold water. Pushing off from the rock ledge, they made for the island and the cave that yawned darkly on one side.

‘The cave’s where the treasure is!’ said Max, putting his head down to plough forward. He swam with choppy strokes and Damien followed, then overtook. He kept being shunted off course, and it was only after a third readjustment that he realised how powerful the current was. As they neared the cave he felt himself being sucked towards the deep opening in the rock – he figured the cave must run all the way through to the other side of the island. Swimming through it would be a worthy challenge, an adventure in lieu of the surf they’d missed.