Once more down the steel ladder. I was getting used to it. The handful of sailors who had been on deck waited for us to pass. Within, the strong, somewhat peppery smell of hot oil from the Diesel engines floated, and there was to be heard a hard, powerful knocking-spitting sound from the same source. The hatch cover was secured, a listener might have heard a steely thump and a grind as it closed. Men stood calmly by the depth gauges and the valves. Not being a "crash dive," the feat of getting under was accomplished quietly, accomplished with no more fracas than accompanies the running of a motor car up to a door. One instant we were on the surface, the next instant we were under, and the lean black arrow on the broad moon-faced depth gauge was beginning to creep from ten to fifteen, from fifteen to twenty, from twenty to twenty-five.... The clatter of the Diesel engine had ceased; in its place rose a low hum. And of course there was no alteration of light, nothing but that steady electric glow on those cold, clean bulging walls. "What's the programme, now?" "We are going down the bay a bit, put up our periscope, pick up the Britisher, and fire an imaginary tin fish at him. After each shot, we come to the surface for an instant to let him know we've had our turn." "What depth are we now?" "Only fifty-five feet." "What depth can you go?" "The Navy Regulations forbid our descending more than two hundred feet. Subs are always hiking around about fifty or seventy-five feet under, just deep enough to be well under the keel of anything going by." "Where are we now?" "Pretty close to the mouth of the bay. I'm going to shove up the periscope in a few minutes." The captain gave an order, the arrow on the dial retreated towards the left. "Keep her there." He applied his eye to the periscope. A strange, watery green light poured out of the lens, and focussing in his eye, lit the ball with wild demoniac glare. A consultation ensued between the captain and his junior. "Do you see her?" "Yes, she is in a line with that little white barn on the island.... She's heading down the bay now.... So many points this way (this last direction to the helmsman) ... there she is ... she's making about twelve ... she's turning, coming back ... steady ... five, ... six ... Fire!" There was a rush, a clatter, and a stir and the boat rose evenly to the surface. "Here, take a look at her," said the captain, pushing me towards the periscope. I fitted the eyepieces (they might have been those of field glasses embedded in the tube) to my eyes, and beheld again the outer world. The kind of a world one might see in a crystal, a mirror world, a glass world, but a remarkably clear little world. And as I peered, a drop of water cast up by some wave touched the outer lens of the tube, and a trickle big as a deluge slid down the visionary bay.