"Dive! Dive! Dive!" Ohh this can only end well. "Set depth one five-zero." That's actually quite deep... "All compartments report conditions normal on the dive." I look down and judging by the lack of rising Atlantic around my knees, I concur. "We're passing over the abyss, depth beneath keel is five thousand feet." Now THAT'S deep. "Alright, let's go deep." We don't actually have to take a look, do we? "Make turns for ten knots, depth one thousand, six hundred feet." WHAT?! "Chief of the Watch aye, make turns for ten knots, make my depth one thousand six hundred feet, twenty degree down angle on the bow."

Umm, what's that sound? "Ohh, that's just the hull compressing." Aha. "The weight of the water above us is increasing, compressing the hu..." WE'RE BEING CRUSHED! "Well, actually, yes. But the aim is not to go much further so that we avoid that fate." Which, I think to myself, is precisely why I'm having to hold on to the railing to keep upright as we nosedive past 800 feet.

Quite loud and jolting noises of compression reverberate through the boat as we pass 1,000 feet. "Umm, Aaron...?" Ohh, I just, uhh... "Feinted?" Yes, that might describe what just happened quite well actually. "We'll, we've stopped descending, you'll be happy to know." Ohh thank Ägir...

The silent, and rather quite compressed, service holds a deep fascination [That's the first and last submarine pun you're allowed -Ed] for many. In the black and white days of U-Boats and the Battle of the Atlantic it was a real game of cat and mouse which usually ended in soggy shootouts as convoys met Wolfpacks, and Wolfpacks met aerial patrols.