“We must go deeper,” Cousteau says. He is haggard, worn to bone, his splendid Gallic nose a wedge driven into his face.

He uses his utensils to illustrate — his fork has become a crane, his spoon the diving machine, a pool of sauce the ocean. I feel the ship roll under my feet, an undulation as gentle as a breath.

Mais oui!” a chorus of voices sings out. “Deeper!”

I’m working my way round the cramped table, pouring coffee into a desolation of plates, cutlery, crusts of bread and fish bones. “But why?” I hear myself asking. “Haven’t we gone deep enough? What crime have we committed that we don’t deserve to see a port, a tree, the inside of a good brasserie?”

Twenty pairs of eyes settle on me. I can see that this last bit about the brasserie is having its effect. Cousteau glances up. “I will never rest,” he says, “until I see with my own two eyes what lies on the bottom. Who knows what miracles will be revealed, what kaleidoscopic vistas of the unknown and silent world?”

I bite my …