The water was already up to their knees when Larraitz shone her torch down the entrance passage and realised they weren’t going to get out that way. Outside, the tide was coming in; inside, the current was pushing hard towards the back of the cave.
That morning, at the harbour, Ramón, the old barnacle-picker, had warned them: “Go in while the tide’s going out and come out before two hours have passed since low tide, which is at twelve today. The entrance passage is the first thing to flood.” They told him they’d be back by two, and at a quarter past eleven they went into the cave with a head torch, an eight-hour glow stick and a bar of chocolate.
Inside, the cave opened out into galleries. Climbing over some rocks, they found a high, dry chamber, with hundreds of bats hanging from the ceiling, next to a crack that let in a thread of light. It was so narrow that not even a cat could have squeezed through. There, among patterns in the rock and echoes, they lost all track of time.
When Larraitz took her phone out of the waterproof pouch, it was twenty to three.
Now, with the water at their knees, Iker pointed at the walls of the passage, covered in barnacles and seaweed right up to the ceiling. “We swim. It’s only fifty metres.”
Larraitz shook her head. She remembered something else: the walls of the high chamber, smooth and dry, without a single shell. “We go back up,” she said. “The sea doesn’t reach up there. And Ramón knows we were supposed to be back by two.”
In the chamber, Larraitz switched off the head torch, which was already down to half its battery, and snapped the glow stick. A soft glow tinted the rock. Iker shared out the chocolate in exactly eight squares.
“High tide is around six,” Larraitz murmured. “Then the sea starts to go out. We just have to be patient.”