Ys, The Ocean of

Artificial circumstellar ocean world

The Ocean of Ys
Image from Steve Bowers
The cilia extruding from the surface of Ys extend beyond geostationary orbit and act as space elevators and as light collection apparatus

Ys -Data Panel

(Pronounced Eess)
The World of Light and Water
StarHD 181144
ClassF5V (Originally F8iv)
Distance from Sol119ly
AllegianceZoefic Biopolity
Infrastructure:Two statite shells sit above the poles of the primary at 0.2 AU, and can be used for power collection or to reflect additional energy towards the torus.

Starlifting apparatus, mass beams and six DWIZs orbit the equatorial plane at 0.5 AU. All are currently inactive.

The Ocean Torus, often referred to as The Ocean of Ys, or simply Ys, encircles the primary at a distance of 2.5 AU
Population14 trillion embodied modosophonts
TravelInside the ocean, most travel is by submarine. This makes the depths relatively inaccessible by the standards on many megastructures. The atmosphere layer is host to many vehicles, from single omnicraft to giant pleasure-cruise airships. The external surface of the membrane, open to vacuum, contains extensive transport infrastructure: Maglev tracks for short distances, and interplanetary boostbeam emitters for longer journeys from one segment of the torus to another. Spaceports and outward-facing boostbeam emitters serve craft travelling to and from the rest of the system.
StargatesRiver of Life, to Ecotopia (1km gauge)
BeamlinesTwo routes, Odet and Auray
Visa RestrictionsOpen access

The Ocean Torus

Minor Radius7000km
Major Radius375 million km (2.5 AU)
Tangential velocity for minor radius3.2 km/s
Period from minor period2 hours, 46 minutes
Mass3.62x10e29kg (Approximately 190 Jovian masses, or 0.18 Solar masses)
Effective surface gravity0.05 m/s2
Pressure at core0.175 GPa


The Ocean of Ys is on record as being the largest single oceanic habitat, and indeed the largest contiguous body of liquid water, in the Terragen sphere. It has been claimed that every aquatic clade can be found somewhere in the torus. While is not true (Some commentators have listed over a thousand aquatic clades whose members have never been in system), many well-known aquatic clades are represented, from dolphins to golden submersible vecs. (Reports of Harren sightings in the lower depths, however, are almost certainly false.)

Megastructures composed of water face a problem of density. As the size of a body of water increases, it quickly becomes self-gravitating, and consequently the pressure in the deepest regions becomes unmanageable. For a sphere 5000km in diameter, the pressure at the centre is on the order of a gigapascal — enough to form ice-VI at 273K.

The structure of Ys counteracts that tendency. First, to increase the available volume, the habitat is shaped into a circumstellar torus like a smoke ring or hoopworld. But this is insufficient: With a minor radius of 7000 km, the gravitational acceleration is enough to turn most of the volume into high-pressure ice. To counteract this, the torus also rotates around its long axis like a topopolis.

The gravitational acceleration inside a cylinder of constant density is inversely proportional to the distance from the axis . So is centrifugal acceleration — but in the opposite direction. It follows from this that at the right speed, the centrifugal acceleration counters the gravitational acceleration across the cylinder.

In fact, Ys rotates slightly slower than this, leaving the surface with an effective surface gravity of 0.05m/s^2. The outer layer of the water is covered with a kilometre deep oxygen-nitrogen atmosphere at 100kPa (standard pressure). A kilometre-thick biological membrane sits above the atmosphere and balances out the atmospheric pressure with its weight.

A self-gravitating torus is vulnerable to bead instabilities, where water concentrated on one spot along the hoop. To counter this, the ocean of Ys is equipped with a complex dynamic management system to keep the water evenly distributed.


Following with the bioist leanings of Ys, the membrane of the ring is alive. It is a common misconception that they are a variant of canopy plants. In fact, each membrane element, a hexagon some 80km on a side and a kilometre thick, is an organism derived from ctenophores, or comb jellies. They are heavy enough to weigh down the atmosphere and create a standard pressure.

The interior of a membrane element has three different structures. First, most of the volume is occupied by a photosynthetic, bioluminescent jelly. This jelly is variably transparent, and can be used to vary the amount of light falling on the ocean below. Second, large, fully transparent protein crystal penetrate the jelly in multiple places. They are used for directing very bright light into the ocean through the filigree (see below). Third, a body cavity in the centre of the organism, about a kilometre across, links two mouths on either face of the element, and serves as an airlock and spaceport for traffic. A thick later of liquid plasm on each mouth ensures no water escapes.

The external cilia extend several hundred kilometres into space. They may be used as beanstalks for spacecraft. More often, though, they flatten into thin organic mirrors. These mirrors form a complex system directing sunlight to where it is needed most. They keep the rear of the torus lit. They allow a day/night cycle. They vary the internal temperature of the ocean to create tropical and polar zones. Finally, the mirrors are also used as solar sails: In the construction phase, they helped spin up the torus; currently they maintain the spin against frictional losses.

The internal cilia hang down between ten and a hundred kilometres into the ocean below. Here, they share nutrients with other parts of the ecology, can be used to generate (or counter) winds, waves and shallow currents. In many places, shallow habitats are hung directly from the cilia.

Membrane elements have large but simple nervous systems, augmented with peptide processors. They are not individually sentient, but collectively form a large part of Ys' local net.

Plankton Processors Ocean of Ys
Image from Gabrielle of Gaussia

Plankton processors and Angel Jellies

Roughly 30% of the plankton in Ys is capable of computation using peptide processors. They communicate using long-chain molecules, bioluminescence, or sound, depending on bandwidth and transmission distance. Though each individual processor is small, together they form a vast and powerful parallel computer linking all local biocomputers in the membranes and habitats. This communication gives the ocean a constant background of flickering, shimmering light and growling noises (most of which is invisible and inaudible to baseline humans).

A portion of the plankton has pseudopod actuators and microscopic bushbot legs, making a form of distributed oceanic plasm and serving as a major part of the angelnet. Angel Jellies are neogens between one and twenty metres across that resemble a simple jellyfish. Like the plankton, they use peptide processors across most of their mass, communicate with chemicals, light, and sound. Though they have very powerful processors, they are not sentient' they are merely nodes in the local net.

The Jellies serve other purposes: They consume waste organic matter and break it down to local nutrients. They can generate both plankton and a pale, waxy substance than any inhabitant of the torus can eat. Storing large quantities of energy in biological torsion batteries, they charge themselves at the surface (sometime they are given energy by the membrane animals), then descend to the depths and release the energy in the form of heat and food.


There are an immense variety of habitat structures spread across Ys. They may serve as cities, breeding grounds, cleaning stations, nature reserves, or simply parks.

Habitats with centrifugal gravity are usually spindle-shaped between two to ten kilometres long and 500 metres to two kilometres wide. The structure is composed of two inorganic shells, grown by gengineered coral and bacteria. The inner shell rotates on magnetic bearings, while the outer shell is stationary relative to the water. Entrance hatches are placed at both ends of the spindle. The interior may be mostly filled with air, leaving only a shallow water environment on the inside surface. Such spindle habitats are usually mobile. Often they are fitted with undulating fins to propel them through the water. Alternately, a pair of counter-rotating spindle habitats without an outer shell may be fitted with helical flanges, allowing them to propel themselves through the water using their rotation.

Stationary cities are platforms hanging from the membrane cilia. They, too, are usually grown of coral. Varying the depth of the platform allows various depths of water to be simulated. Stationary habitats are often fitted with walls to act as wavebreaks. Such platforms may have an area of hundreds of square kilometres.

A new form of habitat is becoming popular in the current era. These habitats are grown on the back of immense sea turtles that swim slowly near the ocean's surface, but can slow dive to different depths if needed.

Finally, some non-aquatic habitats hang in the open air above the ocean surface, anchored to the cilia. Their milligee enviroment may house freebirds, low-gravity tweaks, or just nearbaselines.

The habitat environment varies. The earliest habitats were groves of trees in a shallow lake (modelled after amphisapien cities) or cleaning station reefs for the Madi, but in the current era intertidal zones, estuaries, kelp forests, and hydrothermal vents are all well represented.


Filigree are rotating tubes of air winding through the ocean, anywhere between a hundred metres and five kilometres in diameter and many thousands of kilometres long. Hundreds of concentric cylinders of plasm surround the tube. The plasm pushes the water to rotate around the tube: The outermost layer is stationary with respect to the ocean, but as one approaches the centre, the speed increases. As a result of this rotation, the surface of the tube — where the water meets the air — has its own pseudogravity, like an O'Neill cylinder.

When filigree meet the surface (not all do), they broaden into a funnel-shape mouth surrounded by rings of slow-moving water.

Filigree serve three purposes. First, they allow airbreathing sophonts, such as the original amphisapien colonists, dolphins, whales and manatees, to progress to greater depths without having to rely on respirocytes. Second, they allow light to penetrate much deeper into the ocean, o illuminate the interior of the torus which would otherwise be completely dark. Finally, moving more filigree into a particular region will lower the average density of that region, helping to combat beat instabilities.

The interior of an illumination filigree can be bright enough to harm unprotected sophonts, especially near the surface of the torus. In this case, the layers of plasm will usually prevent entry.

Angel Jellies are often seen breaching inside filigree to reach the centre, so they can send optical signals down its length with attenuation.

Because some parts of the filigree network are in motion, travellers are advised to check the schedule before departing.

Image from Steve Bowers
Lightworms are mobile extensions of Pantagruelars that help to illuminate the dark depths of this vast ocean

Luminous Pantagruelaurs

Even with a managed ecology and filigree network, the deepest parts of the Ys ocean, at the core of the torus, tend to be dark, lifeless places.

To help counteract this, the Luminous Pantagruelaurs were created in 8300, a commission by S3 Red Star M'Pire artist Palaeohermeneutic Phylogeny.

The Pantagruelaurs are vast (between 5 and 100km across), irregularly shaped colonial organisms built from 50 gengineered or neogenic species. At the core of each one are a set of conversion reactors that use the surrounding water as fuel. Layers of radiotrophic fungus coats each reactor. Thermosynthetic tube worms sit with their head near the boiling output and their tail in the water outside. Light from the reaction is shunted though transparent protein crystals and either directed to forests of kelp or to the ocean outside. Parts of the skin can also served as biological phased array lamps. Either way, the light goes up though deep filigree and into the surround ocean.

Pantagruelaurs are S1 transapients. They show variation in personality. Some are gregarious, others retreating. Many have their own project. At least one seems to have obtained and provolved a community of Guanche golden submersible vecs. Another regularly releases gigantic, tentacled and clawed beasts into the ocean above; though apparently aggressive, these beasts are highly diffuse, come apart at a slight touch, and eventually break up into clouds of highly nutritious plankton.

There are currently 723 Pantagruelaurs on record, but there may be many more undiscovered..

Temperature and dynamic stabilisation

The illumination and consequent surface temperature varies continuously across the minor axis. There are two arctic regions with an average temperature of -2 degrees C and two tropical regions with an average temperature of 35 degrees C, each alternating and separated by a quarter turn. These arctic and tropical bands run all the way around the major axis. The arctic regions are cold enough to form ice caps — or, rather, ice lines, that run across the entire torus. They are a favoured habitat of some supenguin groups.

The temperature bands are given a slight helical twist across the length of the torus, turning sixteen times before they meet up again. The effect is visible through the membranes.

Because of sunlight penetrating the filigree and the heating effect of the membrane's inner cilia, the ocean's thermocline is much deeper than it would be on a planetary surface. Surface temperatures remain roughly constant for some 300km below the surface, and slowly converge on 2-3 degreesC over the next 500km. Near the core, the water warms in some places again due to the Pantagruelaurs

The membrane's cilia can also induce winds and shallow (up to 50km) currents. For deeper currents, the local systems induce thermohaline circulation: The plankton and jellies sequester or release salt. The Pantagruelaurs and membranes release more or less heat into the water as necessary. Moving more filigree into a region will decrease its density and increase its temperature. Working in concert, these systems stabilise the mass distribution across the torus and prevent it from breaking up.


The earliest colonies around Ys date from 3500, when a group of Madi arrived from the Deeper Covenant. The system's lone planet — a MesoJovian orbiting at 3.7 AU from the primary — held a number of water-rich moons, which the new colonists mined to use in their habitats.

The culture developed slowly, linked to the outside galaxy by a single, rare beamline. Its inhabitants were more interested in their own habitat art and meditative dances than the business in the outside galaxy. In time, they extracted all the available water from the moons; the planet ended up surrounded by a band of knotted aquaria and oceanic freespheres.

Over time, the system attracted other colonists from multiple clades — Europans, Iniliak, and others. The Madi, lacking any sort of territorial instinct and possessing more living volume than they needed for their population, invited the new colonists to share their habitats.

At the same time, the new colonists brought an extra dynamism to the system. With the moons exhausted, an idea was put forth: Mine the planet's atmosphere and construct a DWIZ to synthesise oxygen and produce water for more habitats. The population voted strongly in favour, and in 4970 the system was put to use. The DWIZ worked continuously, and indeed produced water at a greater rate than the population made use of. The extra water was stored as ice in a lower orbit.

The next big change came in 5453, when, after a period of negotiation with the current inhabitants, a siblinghood of young Amphisapien colonists from the Zoeific Biopolity arrived in system. With them they brought a strong bioist and co-operative ethic and a certain grandiosity of vision. For the next centuries a new culture blossomed.

Some of the main drivers during this time were two Madi: Left-Sweep, a Undyo monk and category theorist, who planned to swim around a star and see what connection it gave him to the ineffable; and Tail-Flick, a well know habitat artist who had recently returned from a tour of Kiyoshi.

The question of how to use the excess water had been batted around some time. Out of the new culture, an ambitious (or, as more than one conservative commentator said, "arrogant") plan came forth: The construction of a circumstellar ocean torus. The plan barely passed vote.

Construction began in 5700. The stockpiled water was quickly used. Some of the habitats were given up by their caretakers and added. Meanwhile, the DWIZ continued to operate, producing oxygen for the water and carbon, nitrogen and other trace elements for the planned ecosystem.

The earliest form of the ring was completed in 6300. Its minor radius was only two kilometres, with a mass less than half Earth's moon, and its membrane was a simple composite sheet, like that of a freesphere. The colonists moved in. The Europans set up a small, independent polity along one segment of the ring, while the Madi and Amphisapiens settled for a more diffuse, open society with no territorial boundaries. Left-Sweep began his journey around the torus.

Over the following years, to torus began to grow slowly. The new generation children of the original siblinghood, proposed new ways to enhance their megastructure. Of particular importance here is the Amphisapien mystic-geneticist Jaashi, who designed plans for a new biological membrane based on ctenophores (the genome of which they had on file), and introduced an early form of the jellies.

By 7000, the torus had grown to a respectable radius of 300km,with a relatively slow spin about its minor axis to counteract building pressure near the centre. The systems mining the planet were shut-off and left inactive.

By now, Ys had acquired some degree of fame as an aquatic megastructure in the surrounding systems. New colonists of many aquatic clades, from the ancient and venerable dolphins to the (at the time) young Kanumae arrived to seek out their place in the ring. There was enough room for all. The original builders voted to allow free immigration the time being — but a vote to allow the new arrivals voting rights about the fate of the ocean itself did not pass.

In 7215, Jaashi ascended to the first toposophic. To accommodate her new mind, she took on the form of a giant serpent, covered with bioluminescent strips and chromatophores. Though she continued to work on the biological aspects of the torus, she retreated from most of her political life. The exception was in 7300, the 1000th anniversary of the ocean, when she made a five-year long tour across various parts of the ocean in her new body, aided by a number of avatars.

By 7500, the number of colonists had grown rapidly. Though there was was plenty of space and resources for all, tensions were rising. Some groups had taken an almost hider-like lifestyle. Of these, a small subset had begun to raid other groups, apparently for no other reason than sport. Other groups had consolidated in response, becoming inward-looking polities intent on keeping the raiders out. Meanwhile, a old and well-respected Kanuma, Roahrr, was gaining ground in per calls to expand the ring again — and to be allowed the voting rights that accommodate the new population.

With Jaashi less involved and Left Sweep willing to communicate but not stop his journey, the original builders had begun to diverge. A majority of the Madi were disinterested by what happened elsewhere in the torus. The original Europan polity has ossified, with some of its less conservative members joining the raiders. Many of the first-generations Amphisapiens were too wrapped up in the habitat designs, and settled to pointing out that the raids never actually injured a sophont.

This was to change a few years later. When one of the smaller polities — a mini-kingdom of Megapteras — was raided, the king immediately declared that the entire polity, some three thousand sophonts, pursue the raiders and imprison them, "To clear the great ocean of this scourge."

Some of the raiders returned to their apparently staid lives among the Europans. The Europan polity forbade the arrest team from entering. The arrest team called on their allies, and a brief war ensued, leading to the temporary death of six hundred sophonts and the permanent death of seven more who were not backed up.

The battle served as a flashpoint. It was enough to catch the interest of the Amphisapiens, many of the Madi, and Jaashi herself. At last it became clear something had to change. Even Left-Sweep, communicating through the local net, expressed distaste for what had become of the polity. After years of discussion, during which Jaashi listened to hundreds of accounts and suggestions, a constitution was drafted, guaranteeing freedom from harm and harassment, and of movement, resource-access, and voting rights. Every inhabitant was given a vote, and the the response was overwhelmingly positive. At the same time, within those limits, the inhabitants were given a wide degree of freedom to associate as they wish.

Over the next few decades, the society roiled as its inhabitants worked out their newfound freedoms and limits. In 7603, Roahrr again proposed expanding the ocean. Left-Sweep signalled his support, as did Jaashi. The vote came out in favour.

The project gained an enthusiastic following, with many excited about the grand new project and eager to contribute. Jaashi advised the engineers on how to manage such a large quantity of water, and in 7605 the ocean began to expand again. The remains of the planet were consumed. But this wasn't enough for the new expansion, which needed tens of jovian masses to continue.

More DWIZs were constructed, along with original, and placed in an orbit inside the torus. For over a millennium, starlifting equipment spun hydrogen off the equator. Mass streams carried it to the ring of six DWIZs, then carried the water output to the ring where the membrane animals consumed it, transferred it to the ocean, and slowly increased its rotation.

Following discussions of exploratory value, it was decided that though the angelnet would protect the inhabitants according to the constitution, it would not automatically provide information about the entire ocean. In effect, great volumes of water — especially in the core — became known only to Jaashi. The inhabitants were free to share information with each other over the local net, of course — but first, they would have to discover it. In time, this feature gave rise to a new exploratory culture known as the Piccardians.

In 8120, Jaashi breached the second toposophic, transferring her intelligence entirely to the membrane. Shortly after, in 8200, Ys was connected to the nexus by a microgauge wormhole.

By 8690, the torus had reached its current size. By this time, enough material had been taken to change the type of the star, cooling it down to F5V. A vote to stop the expansion was finally passed. The starlifting structures and DWIZs around the star were deactivated but left in place, should the inhabitants wish to expand the ring again.

To celebrate the 3000th anniversary of Ys, the first Luminous Pantagruelaurs were added in 9300.

As of 10600, Left-Sweep has been swimming for 4,300 years. At his so-far maintained average speed of 15km/h, he will need to swim for another 13,500 years to complete his journey, which he should finish sometime in 21,100 AT. A great deal folklore, from jokes to actual beliefs, has sprung up around the completion. The more unlikely tales say that upon completion, he will spontaneously transcend to archailect level. More grounded claims say he will unite with Jaashi, and both will leave Ys; when they do, the cultural harmony will break down without their guidance, and eventually the dynamic stabilisations systems will fail and the torus will break apart.


The Aquascapers are a a diverse and influential group who grew out of the original Madi landscape architects. They specialise in creating new habitats, landscaping them, and maintaining them for the population of the ring. A core of the group specialise in neogenics and ecopoesis for their habitats. The aesthetic standards vary wildly: There are seven different "classicist" groups with conservative, well-defined aesthetic ideals (all opposed to each other), plus a broad spectrum of individuals who compete to create ever more original and bizarre interiors.

The Piccardans make it their mission to chart and explore the vast core of the ocean. They regularly send out expeditions from their habitats into the depths to seek out new clades and new Pantagruelaurs. The more extreme work with stringent limitations on equipment, and sometimes without backups, asking the local net to excuse them from the safety web. Some compete, and some die. Because the inner ocean is constantly, though slowly, changing, their work can never be complete.

The Scrappers grew out of the original raider cultures that plagued the torus in the 7500s. In the current era, raids have been turned into a sort of team sport. Each group holds some false, easily noticeable fake goods, and other groups attempt the obtain the goods on period raids. Most raids encourage actual violence, and a backup is usually mandatory for participants.

The Meditators of the Flux are a nomad group with an unusual ethos. They simply relax, and allow the complex currents of Ys to carry them wherever they may. They usually travel in groups of five or less. Most carry habs and safety equipment with them, should they pulled into the depths. Though the nature of their lifestyle prevents the meditators from physically meeting, they maintain an active community on the local net.

The Webster Song&Dance Collective is a performance culture based on Madi dance-theatre combined with music and audio narration from the xenosophont Singers. Though Madi and Singers still compose most of the membership, other clades are encouraged to participate. The Collective became popular across the ocean for its performance at the 4000th anniversary celebrations in 10300.

Golden Submersibles
Image from Steve Bowers
Golden Submersibles (originally from Guanche), with pendant cities in the background
The ocean depths host many hundreds of cultures and polities, all at something of a remove the shallows. Beside the Pantagruelaurs, the more well-known are:

A population of Golden Submersibles brought from Guanche and provolved to sapience, who sometimes venture out from the body of their caretaker Pantagruelaur. Piccardian explorers describe them as timid but playful.

A number of architeuthis and anomalocaroids. They are rarely communicative, but sometimes produce diamondoid sculptures of deep-water filigree or Pantagruelaurs they have seen, and release these artworks to float up to the shallower layers.

The Abyssids — an aquatic Cthonid tweak clade. The pressure, darkness and physical isolation of the depths suit the Cthonid mentality. Though they avoid physical proximity (for Abyssids, anything less than two kilometres is uncomfortable close), they are one of the more garrulous inhabitants of the local net.

Left-Sweep has grown very famous during his travels, to the point where he was often harassed by tourists. Currently he swims alongside some three hundred decoys, spread out through the shallow waters. The real Left-Sweep, when he makes a rare stop at a cleaning station or habitat, makes himself known as such. The locals may consider this a great honour, or an unwelcome sentimental distraction. Either way, it is extremely rude for anyone to advertise his location on the local net.

Long-term fate

Should the ocean's dynamic stabilisation ever fail, it will eventually collapse and fragment into a large number of bodies. According to simulations, some of these will be thrown out of the system, some with be too small to survive and eventually boil away. But in most cases, at least a quarter of the torus's mass will form a SuperJovian class planet composed almost entirely of water-ice, a thin ocean, and an atmosphere of vapour.

Such a planet is unlikely to form naturally; a discovery of one would point to evidence of a xenosophont structure with a similar design to the torus. Though there are none in Terragen space, one candidate has been observed in the outer Perseus Arm by the Argus Array.
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Development Notes
Text by Liam Jones
Initially published on 19 May 2017.

plankton processor image by Gabrielle of Gaussia added January 2023