The city encroaches it. All great cities are thus, prows built into the waves, the waterfront, shops, houses huddling behind. And the city grows, at first, around harbours, builds its own, houses, neighborhoods expand backwards, up into the hills, into the mountains, or further into the plains, because where else can they? And there comes a point where someone thinks to fill in the sea, and so they do, they build the city out onto artificial spits, islands, fortify it against the waves, build it up, higher and higher, filling it in more and more, raising up the seashore on great concrete piles, carry stones to fill it in, and so always the city is growing into the sea.
And let us for a moment consider the sea. Or the ocean. Or perhaps a great lake or river that abuts the city, but always there is water - London has the Thames, Paris the Seine, Montreal the St Lawrence, Shanghai, Mumbai, Hong Kong - every city worth mentioning has this.
So to the sea. The city, a port that overhangs the abyss, strange creatures that are washed upon the shore, bloated, of no resemblance whatsoever to their former living selves. People gather, those that can stand the smell, to speculate at what this might have been.
Find tidal pools, lagoons filled with starfish, jellyfish, anemones, tiny crabs and barnacles, mussels, look out upon it, the spume of whales in the air, perhaps the leap of dolphins or rays, flying fish, the bark of seals and sea lions, otters crack shells upon their belly, the freighters, ships, sloops and sailboats that ply the waters know virtually nothing of it, every sailor and passenger is cautious of a too familiar acquaintance. They know only their side of the waves, this rippling boundary of worlds.
Consider what lies beneath.
The first few dozens of feet, well, on a clear day you can see this. Perhaps a sandy bottom, crabs, sand dollars, fish. A coral reef filled with life, bright neon fish of every shape and hue. The silhouette of sharks coming into shallow waters, the migration of gentle manatees, these first few feet would reward an entire lifetime of study. Jellyfish gently pulse, sea grass waves.
At night the waves are lit with bioluminescent plankton, footprints are outlined in the sand, splashes in the water generate sprays of light. Waves flicker as they crash into the shore.
These first few feet, we can know this - somewhat - we can see it, watch it.
But what of the Abyss?
For the sea, these first few feet, what we can see, this is nothing of it. Nothing at all. That decomposing monstrosity on the beach surrounded by curious onlookers, that did not come from the first few feet. These first few feet, trying to guess what is in the sea by that is like trying to guess the contents of a book by a single, randomly chosen word.
There are the illustrations and tales of sailors that have plied the seas their entire lives. The documented first-hand accounts of sea monsters, kraken, giant squid attacking galleons, tentacles reaching up from the ocean to pluck their sailors and pull their boats to a watery demise, of prehistoric heads upon lengthy necks, there are tales of ships towed by their anchors towards unknown purposes until in desperation they cut them. Sounding leads are brought up from great depths, flattened by the pressure. There are fish that lose all shape and explode when brought to the surface. There are the accounts of whalers, dinner plate sized scars on whales from their undersea battles with giant squid. Or the ghost ships - the Mary Celeste, The Lady Lovibond, The Baychimo, The Octavius, The Flying Dutchman, ships abandoned or found adrift with - quite literally - skeleton crews, bones tied to the wheel, to the Crows nest, skeletons dangling from the rigging through great swathes of seaweed, masts hissing and crackling with St. Elmo's Fire, phosphorescent ripples light the bow and stern, phantom ships sailing from port to port, emerging through fog, quietly appearing before terrified witnesses only to sail onward on their supernatural errands, to great domed cities and tropical ports appearing on distant horizons, shimmering just above the waves...
And even these mysteries, these are what are passed to us by witnesses - there are countless more, unrecorded, because none survived or returned to tell the tale. What we know, the hearsay, only confirms our ignorance. What of all the vanished lighthouse keepers, the Flannan Isles, for example, one perhaps an accident, but 3? The light lit, dinners on the table - and an uncanny, knowing quiet that speaks of sudden misfortune, the precise circumstances of which will never be known.
Imagine those first occupants of diving bells, watching the sea swarm past through portholes...A giant blown glass diving bell, Venetian, occupants lowered into a harbour, water pressing up through the bottom, wetting their shoes and ankles, earlier even, weighted to the bottom of the sea to gather shells, pearls, salvage cannon from shipwrecks. Great dark shapes pass overhead, shadows against the dappling light. Or Alexander, who surveying the depths from his glass barrel pronounces the world damned. Or John Deane, "The Infernal Diver", weighted and striding along the bottom of the sea, gathering treasures from shipwrecks, his copper and brass helmet fed by hoses from the surface, as deep as he dived he never once plunged into the twilight.
The mind wanders where the body cannot, these few expeditions beneath the wave fuel the legends of great spiraling cities grown of coral and conch shells, ornamented with pearls and fortified with cannon, populated by mermaids and water nymphs, guardians of towers of blackening ingots of silver, flashing doubloons, pieces of eight, gold chains, the viridescent glimmering of emerald and diamond brooches, rings, pendants, strewn upon the sandy bottom, jewels, precious metals, amphora, sculptures, the bric-a-brac of millennia fallen, falling still from that rippling boundary between worlds.
Poseidon now the keeper of fortunes that any, that every king would envy. The gathered riches and plunder of man and pirate rained into the sea. Mermaids, by reputation, Mermen, by implication, guarding those oceanic treasures. The rivers, the lakes, they are guarded by Neptune and the undine spirits.
Beebe and Barton together invent the Bathysphere, a small round sphere that fits 2. Built to withstand incredible the incredible pressures of the depths, the first attempt is a failure - three inches of steel, too heavy to be craned into the sea, and so they reengineer it, build another, more lightweight, and together they make the first, the deepest dives beyond all light, through the twilight zone, cables connecting them to a ship, bringing power, radio, light, fresh air, and finally steel to return them to the surface. These are their umbilical cords.
They are lowered into the abyss, the blackening void. There are two portholes, through which cramped they can look out into the sea. They see deep sea anglerfish, lantern fish, vampire squid, jellyfish. Grotesque blobs and streamers of protoplasm, outlandish goblin sharks, bizarre and fanciful creatures unfamiliar to eyes accustomed to evolution at or near sea level. They see other things too, even more unlikely, that challenge their powers of observation and description. The air is stale, foul, the bathysphere is cold, but they are transfixed. Turning the light off now their eyes adjust - they see the pulsing lures of the anglerfish, the lanternfish, the firefly squid, the vampire squid with it's clouds of luminous ink, plankton flickering like stars in the sky. They reach unprecedented depths. Silence? No, there is always sound, the straining of cables, crackle of the radio, the fan that brings them air, the hum of electricity, the distant song of whales, the clicking of shrimp, hold your breath and strain your ears to hear above the background noise...
Plankton swim and rain past them into the void. They are nowhere near the bottom, the sea might extend through the entire earth for all they know, it's unfathomable, without bottom, below them only the inky black increasing pressure of the abyss.
Something bumps the bathysphere.