Sphere.

The Thames rocked up and down, like a Mother putting her child to sleep. The river would have been packed with other boats and people, but it had been blocked for 5 kilometers in both direction for the occasion. You could’t have anyone know about the work.

My long black coat waved in the breeze like a cape. The three men behind me stood silent, waiting for me to move forward or try and back out. As if I had a choice. I stepped onto the wooden platform that swayed next to the boat. A man behind me called to the captain, then came to join me.

The wooden platform beneath us was thick and solid, meant to cut the sway from the waves. The wood acted like a sort of shock absorber for the large spherical submersible that stood before me. It was perfectly round, with circular windows half opened placed around the sides. I did a walk-around inspection and closed each window as I passed.

The sphere was cool to the touch, cooler than I had been expecting. I almost recoiled as my fingers brushed the metal. It was chrome, and you could see a warped version of your reflection in its face if you looked close enough. I removed my jacket, handed it to the man next to me, and peered into the black waters.

I took a deep breath, and dove in.

My mammalian diving reflex kicked in as soon as I hit the water and I fought the urge to take a breath. I swam under the platform by memory, since the water was too dark to see through. I surfaced in the sphere and gulped down as much air as my lungs could take. I brushed the wet hair out of my face and took a seat on the round bench that circled the interior.

The man looked through the window, and on seeing my thumbs up relayed the message to the waiting ship. He jumped back aboard and the sphere started to rise. They picked me up, pulled the platform from under me, and I hit the water.

The air bubble inside kept the waves just lapping at the opening near my feet, but it's a sight you never get used to. It feels as if at any moment the bubble might burst, the egg might fill with water, your shelter will become your tomb, and you’ll drown. Sitting on the cusp of your own demise, waiting to be swallowed by the cold darkness you’ve submerged yourself in. Watching the waves lap at my feet.

London has a secret history. It's almost common knowledge now that the City of London is a separate entity inside the city we know as London. The deeper truth lies beneath even that. London, and The City of London were built on another, older city, back before even the Roman occupation.

This ancient city, whose name was lost to time, still houses almost all the utilities still in use, much like how Roman roads are used today. There was nothing wrong with the construction (in fact, it may be of an even higher quality) so they were never abandoned. It does make fixing a bit more taxing, a bit more specialized. When something goes wrong, they call me.

I sank deeper and deeper, until I saw the flashing marker telling me I had fallen one thousand meters beneath the waves.

I was tethered to the surface by means of cable but it’s easy to forget this far below. It seemed like I was falling faster, but I knew it was an illusion.

I sank and sank, farther than you’d expect the river to go, over a kilometer and a half beneath the London streets. I started to see the ruins left by a civilization long past. Their curling spires pierced the water, and looked undamaged aside from the moss and seaweed growing along their sides. The matter grew on the abandoned buildings, fostering their growth and also preserving the ancient structures. The way it moved gave the sense it was all one organism.

I touched down on the river bed and donned the suit that sat under the bench. I stepped out on the riverbed and felt the water tugging me back towards the capsule. I pressed further to the city, the way lit sporadically by poles rising from the sand, casting out small orbs of light.

The city was beautiful. It was constructed from glass and stone, and had stood being weathered by age and water. Most of the windows remained complete, only made murky by the waves and sediment dragged up by the tides. In the place of London’s domes and towers, it had spires and curling cones. The buildings all shared an organic twist.

And yet, something was different. I looked about, walking towards the main street. I walked from lamp to lamp, skirting through the darkness. Something in the corner of my eye moved, and I thought a tower had fallen. I peered up, trying to see through the thick water, and saw a massive point slip away. The tentacle slid through the spires, gliding back to the darkness. I felt my heart in my throat. I felt the blood pumping into my brain. I felt my knees quiver but they would not move.

From the dark, off to the left of my vision, an inky black arm shot out faster than I could react. It smashed into the chrome sphere, knocking it aside like a rock on the road. All was still again. I was alone, as abandoned as the city.

The moon rose over the tallest spire, a bright yellow crescent. It contracted, and I was alone no more.