There is a flash of lightning and a hundred shipwrecks are visible at once, some awkwardly stacked on top of each other, ancient masts skewering the hulls of newer ships, and broken glass covering the entire ocean floor. Methane gas starts to seep out of the crack in a window of a building in the middle of all this, and the gas becomes bubbles and water rushes in. After a few tries, the glass yawns like an oyster and lets out all the methane it can in a great bubble and then it snaps shut again.
Inside the window, there is a room now filled mostly with water and bobbing wooden debris. The window is round, bulging, and so are the walls of the room. Where the highwatermark goes, straight like a ruler, the unescaped methane from somewhere beneath this tectonic plate takes over. Every time the ocean pressure becomes strong enough to open the crack – like squeezing a tennis ball with a slit in it – the gas is let out, and water rushes in again, and the crack grows just a little bit wider.
Over the months, the wooden debris will soak up enough water to sink to the floor and the water level will follow. The water will continue to sink through a grill-hatch down to a spiral staircase covered in patient algae, half-alive, and the water will continue sinking, trying to reach the point where the staircase ceases to be a staircase and is just a gorge, until it ceases to be a gorge and shrinks to a crack. It will sink towards this because, every so often, a bubble of gas will struggle free from the crack and travel upwards, catching itself on algae on its circuitous route up. The algae is brimming with minuscule remnants of the bubbles.
There are three sets of glassware in this tower: one massive cupola, one huge lightbulb, and one drinking glass. When the water sinks far enough, there will still be water left in this drinking glass, which stands upright on the table every time, though it’s knocked about when the water floods in. The cupola, covering the lightbulb, is filled with water too, and it takes much longer for it to dry out, and it needs to dry out completely. Sparks fly, then, and the lightbulb inside lights up for a brief few moments.
This is when the ocean squeezes the lighthouse until it opens its tiny mouth and breathes out its methane soul and lets the cold water in and everything goes dark again. Sometimes, a ship is caught in the bubble and it’s as though the sea stops existing underneath it for a good ten seconds, and the ship falls and the ocean closes around it again.