Making an Island/Printable version

Making an Island

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Urban PlanningEdit

Palm Jumeirah in Dubai, an artificial archipelago.

In areas where space for living or activities are extremely limited, land reclamation and island building is often used to create usable space where there was once none. This is particularly useful in urban coastal cities, which are often built up right next to the coast.

Real Life Examples

  • Building a major airport takes up a lot of land, often requiring it to be placed far away from the city center, and eliciting protests from residents disturbed by the noise and traffic it creates. Artificial islands avert such problems by placing the airport in the sea next to the bustling city center, as is the cast with Chubu Centrair International Airport in Nagoya.
  • The creation of waterfront living-space is also desirable to many, and artificial land projects such as the Palm Jumeirah in Dubai serve both to create living space, and as a prestige project that increases the status of the city as a cutting edge space.

Infrastructure SupportEdit

An artificial island being built to construct a bridge pylon.

While not the most exciting function for an artificial island, creating small islands to support infrastructure is perhaps one of the most useful applications of artificial islands.

Another infrastructure use for artificial islands includes creating a base for a lighthouse, as was done for the Cheboygan Crib Light in the Cheboygan River.

Environmental SupportEdit

Floating artificial islands are relatively straightforward to deploy, and have a number of ecologically beneficial uses. For example, artificial floating islands have been deployed as scaffolding for plant life in heavily polluted areas, giving support to struggling wildlife populations.[1]

Home ImprovementEdit

In rural areas it is common to build artificial ponds on a property, both for recreation and for practicality. Building an artificial island in the pond can create a unique space for secluded activities.


The Principality of Sealand, a repurposed defense platform. This is perhaps the closest to an successful artificial permanent living space that has been achieved.
Concept render of Andras Gyofi, a concept of a seasteading community. A similar real artificial island has yet to be realized.

Seasteading is a movement that seeks to make the sea habitable. Many Seasteaders value the freedom of being outside the territorial waters of a state, and many simply want to be pioneers, homesteading a new frontier. While a full description of the seasteader movement is beyond the scope of this book, it should be noted that Seasteaders greatly value the idea of artificial islands for both philosophical and practical reasons. While seasteading can incorporate a number of concepts, typically either artificial platforms or simply living on ships, the idea of making an artificial island to permanently inhabit appeals to many.

Of course, inhabiting artificial islands outside the territorial claims of existing nation states must deal with the same problems as natural islands far from the mainland, primarily relating to either safety or logistics. Thus only the most dedicated seasteaders attempt this route.



This chapter describes some of the possible methods for creating an island.

Dumping MethodEdit

The easiest and most straightforward method is to import large quantities of rocks and soil into a shallow pool of water until the hill it forms breaks the surface.


  • Solid foundation - If you want your island to stay in one place no matter what kind of storm hits it, it's hard to beat a solid mass.
  • Simple - Easy to conceptualize.


  • Expensive - Dirt and rock are actually quite valuable in large quantities. Beyond raw material cost, transportation of these heavy materials is hard and costly.
  • Not movable - Sometimes, being able to move an island is quite desirable.
  • Must be placed in shallow water, unless you have a really huge amount of material.
  • Expansion requires enough material to fill a volume from your extended surface to the sea floor i.e. 10 m^2 of extra land in 10 m of water will require at least 100 meters cubed of material.
  • Erosion will be a problem without some way to hold the island together.

Rishi Sowa's Floating methodEdit

Get broken fishnets from trash and fill with empty plastic bottles, tie to discarded wooden pallets, or bamboo lattice work. To make it larger you tie additional segments together. Cover the pallets or latticework on soil, plant mangroves and other salt tolerant plants. The roots will help stabilize the structure and provide nourishment. Further information available at .


  • Free
  • Environmentally friendly


  • Vulnerable to violent storms (could sink)

General Floating IslandEdit


  • Movable
  • Can be placed anywhere
  • If built as a set of modules then expansion is almost unlimited


  • No foundation for building
  • Poor anchors will result in island drifting
  • Storm damage may be more severe as center of gravity is much higher compared to a normal sea floor constructed island

Biorock MethodEdit

Close up of electrified rebar with Biorock forming on top of it.

This method utilizes electricity to cause minerals to be deposited onto a mesh of conductive wire. Over time it will form a substance similar in strength to concrete.


  • Construction is inexpensive. Cost is the price of the mesh foundation and the electricity required to form the biorock.
  • Massive structures can be built.
  • Biorock structures may become the basis of new reefs


  • Will require moderately shallow water
  • Could take long periods of time depending on conditions.

Large Ship MethodEdit

MS Satoshi in 2021.

Most expensive method compared to any listed above. The MS Satoshi served as a real life example of this concept from 2020 to 2021.

This method is common in fiction. This method was depicted in the movie Waterworld and in the book Snowcrash by Neal Stephenson as a place where people made a permanent residence on an abandoned large ship. Snowcrash in particular makes mention of a large inter-connected city of lashed boats connected to a decommissioned aircraft carrier (the U.S.S. Nimitz in this case). With little propulsion it was forced to go with the flow of the sea currents using its engines to only keep away from the territorial waters of countries.

Also the Mindstar series of books by Peter F Hamilton (Mindstar Rising, A Quantum Murder and The Nano Flower) also describe the use of ships and large floating concrete structures in the middle of the Atlantic as a manufacturing facility and spaceport, using large OTEC generators to provide cheap electricity from the thermal difference between deep sea water and surface water.


  • May be used in deep sea oceans without anchorage being strictly necessary.
  • Mobility of structure is possible, with even large power facilities available.
  • Basic utilities and resources such as water purification, power generation, communications, and other basic requirements for survival are usually available and built-in to basic design of ship.
  • Survival of major storms is possible, although deep sea natural phenomena are still not totally understood.
  • May serve as "anchor" to a larger island complex using one or more of the above listed methods.
  • Gives an "instant start" to any island structure, including basic life support and shelter.


  • Expensive
  • Dragging around a "flotilla" of other island structures (like many of those listed above besides this method) may prove difficult at best.
  • Sovereignty claims may be made on the original vessel. Most major ships are usually "flagged" to a specific nation-state, although there are "flags of convince" to many vessels, and it may be possible to find a "stateless" vessel.
  • Any abandoned or decommissioned ship may have significant structural damage, including saltwater corrosion, damaged components, or genuine antique facilities with no spare parts. This may require knowledge of a machine shop to maintain to build custom tools.

Pikecrete/Pykrete MethodEdit

Please refer to materials section for a detailed explanation. Pykrete consists of sawdust mixed with water, which is then frozen. This could potentially be used to create a strong artificial iceberg of sorts.

Pikecrete can serve as an extremely strong island material, it has the same strength as concrete but it floats. It can be used to hold a foundation until a permanent location is found. Alternately, if you would like to roam, just make a mold of a vessel and then pour it onto the mold with a flat top as a foundation. It could also potentially serve as a boxing fence to pour in dirt or sand to form an island.


  • Inexpensive
  • Weather-resistant
  • Good for short-term use
  • Can be applied to the entire construction from sea-bed to above-sea level


  • Will eventually melt unless continuously cooled.
    • Subsequent freezing or refreezing can be costly as well
    • Any failure to power or cooling facilities may lead to imminent structural failure.
  • Using it to construct an entire island can be expensive as a barge with dirt or other, terra-firma materials are needed and can be costly
  • Production of a mold is necessary
  • In practice, hard to actually use.[1]

Note: It may be possible to use these disadvantages as advantages. It should be possible to build a vessel from pykrete and use it to transport raw materials en-masse to the site and then use them. No costly ship to return and this would also be biodegradable.

Volcano MethodEdit

Many islands have been formed as the result of undersea volcanic activity - the Hawaiian Islands are an example. A volcano is simply a point where the molten rock has squeezed through a fissure leading to the surface of the earth. Theoretically if an appropriate point can be found where a volcano can be stimulated by drilling or placement of explosive on the ocean floor, a subsequent eruption may form a cone of lava that reaches above the surface of the water.


  • Creates a sturdy and solid landform; weathering will eventually turn the igneous rock surface into fertile soil.


  • Immensely expensive and disruptive to the local ecology
  • No technology exists to stabilize a volcano once one has been formed
  • Location would be dictated by existing geological structures
  • Would take an extremely long time

Sand Build-up MethodEdit

All you need is water (estuaries/pool of water) and sand/loam. First dump sand/loam into the water. Then when it reaches the sea level carve it with your hands. Do it again and again until it stands on its own.


  • Sturdy if stabilized with plants
  • Plants can be used if loam is used
  • Kid-Friendly - Easy to do on a small scale in a household container.
  • Closely related with Dumping Method


  • Expensive - Sand is quite valuable.
  • Easily eroded
  • Doesn't provide a large amount of quality space.
  • Not suitable for all environments.



Seacrete / Biorock / Mineral accretionEdit

Biorock structure

By using a low electrical current and a metal mesh you can cause minerals to be deposited on the mesh. Rate of deposition is limited by current used, flow rate of water and many other variables. The minerals can grow at the rate of about 5 inches per year depending on the amount of current flowing. The higher the current (amps), the faster that accumulation occurs. This is a fairly environmentally-friendly technique as the only resources it requires that are not easy to provide from a renewable source is the mesh.

Of course, the electricity must also be considered and this will require a source. This could be provided by generators such as solar panels, wind generators, batteries, and the like, but these will require some kind of existing nearby structure or platform to be positioned on.


Concrete is fairly commonly used by artificial island projects.

Concrete is not a particularly 'green' material, as concrete production releases a large amount of carbon dioxide.


Pykrete block after being shot.

Pikecrete is a compound invented by a British scientist named Geoffrey Pyke working under Lord Mountbatten during the Second World War. It consists of ice with 14% sawdust or wood pulp and 86% water mixed into a slurry and frozen. The resulting compound is not only roughly as strong as concrete, but also resists melting and is able to float, being less dense. It also does not suffer from concrete's carbon dioxide output issues.

History Lord Mountbatten threw a small block into Churchill's bath water as he rushed into his house and gave him the idea of building an aircraft carrier (HMS Habakkuk and sister ships) out of pikecrete. The ship would have been larger than anything before or since, and it could resist (unlike normal ships) torpedoes and bullets.

Supposedly, Lord Mountbatten demonstrated this by firing two rounds from his revolver--one at ice which was shattered, and then at the pikecrete which actually bounced off and nicked Admiral Ernest King in the leg, making his point.

Pikecrete theoretically only needs cooling pipes to keep it afloat in tropical waters. Aircraft carriers made of it would therefore have been able to stay afloat, only needing to go to the Arctic every few years for a complete re-freezing.

Currently As of today pikecrete/pykerete is not considered relevant by most scientists. Pykrete is generally only used for glacial reconstruction.

Steel and other metalsEdit

Steel hulls have some great benefits. It's readily available all over the globe, it's not prone to marine borers, it is quite cheap once you come up to a certain scale (some where around 7 meters in diameter for a circular island).

But it certainly has some backsides as well. Since sea water is inherently eroding on almost all metals, the steel has to be protected in some way. The obvious solution to the layman is of course different kinds of paints and varnishes. As one intuitively understands, this not an ecological way, and since it usually demands some re-applying every now and then you might have to see to that your island is capable of being dry docked. Another alternative of conservation, or more correct, for delaying the erosion, is using anodes. The two methods can be combined.

Plastics and ceramicsEdit

Artificial Islands have been made using recycled plastic bottles.

That said, plastics should be used with care. Erosion of plastic leads to micro plastics leaching into water, which has negative environmental impacts.

Construction Guides

Floating FishnetEdit

First of all, it would be better to construct these on land and then transport them to the water.


  • Soil
  • Fishnets
  • Empty bottled water containers and/or empty drink bottles.
    • Make sure the bottles are closed and air tight; preferably plastic.
    • Do not employ glass bottles, they will break!

Here's how to calculate how many bottles you'd need for your island:

  • Calculate how much weight in soil you'll have for the island (in kilograms).
  • Calculate how much weight in other facilities you'll have for the island (in kilograms).
  • Calculate the maximum number of people you expect on the island, and multiply that number by 70 kg.
  • Add the above numbers, altogether, and add about an extra 5~15% of that for safety.
  • The resulting number is the total number of liters in bottles that you'll require. Divide the number by the bottle size (in litres) that you'll be using to get how many of them you need.
  • 250 mL = 0.25 L; 500 mL = 0.5 L


  1. Spread the fishnet over a flat area where plants are able to grow into the soil but not the ground underneath (construct on top of something like concrete).
  2. Figure out how you want the empty bottles to lay in the fishnet. You could try to tie them to the fishnet or just lay them on their sides (if you think the roots of the plants you're going to be using in the next step will secure them in the soil).
  3. Cover with soil and plant plants as hopefully they will trap the bottles in their roots. You will have to determine the depth of the soil you want. If it's too thin your weight won't be dispersed enough and you may fall through. If it's too thick it may simply sink.

Modular ConstructionEdit

It is envisaged that the island will be produced in a modular way, with sections able to be added as required. Modules can be either free floating and anchored to the seabed, possibly using an existing sea mount as the anchor point, or built up from the seabed itself.[1]

Modules can be any shape and design but the easiest shape both to deploy and built is the rectangular platform. Hexagon modules should also be considered for additional reasons. The prime one being increase of volume for a given surface area.[1]

It is suggested that modules should be able to be raised and lowered in the water to allow the modules to be moved as needed. A module completely empty of water has less inertia and will be much easier to control for a tug or other propulsion system. A module half full of water for example will be much more stable as long as that water is prevented from moving from side to side (this is the same principle used for ship-board stabilizers and fuel tanks in cars.) The easiest way to do this is to provide baffles in the buoyancy tanks that prevent fluids from moving from one side of the tank to another.[1]

One design that may be viable is that of a box, solid at all sides except the base which will be covered with either mesh, if an internal lift bag is to be used or solid of all sides with valves able to control airflow into and out of the tank. It is suggested that the tank be divided into several sections to allow for redundancy if a tank should become damaged. It is also suggested that the valves should be designed in such a way that if they fail there is a backup valve able to stop it failing in a dangerous way.[1]

The biggest risk for any island is the destructive force of a storm. A floating island as suggested above should be able to cope with such a storm by increasing the amount of water in it buoyancy tanks. In doing so it will become heavier and sit lower in the water. It will also have less cross-sectional surface area to be pushed against by the wind. The only real problem will be the waves. Wave energy decreases with the depth below the surface. The depth being dependent on the wavelength of the wave. In calmer water the sub-surface effects of waves will be minimal, but during a storm wave-length increases and therefore sub-surface effects do also.[1]

One possibility for a floating island which will be difficult in practice would be to literally sink the island during a storm and re-float it after it has passed. This would probably be a last resort option as it would require a lot of disruption unless the modules were designed for this action.[1]

Compartmentalization of the buoyancy tanks of a module should allow greater tolerance of water ingress by limiting center of gravity shifts through the structure and thus making the module more stable. This can be proved in a little thought experiment. If we have a spherical module, unlikely but it makes it easier to demonstrate the basic idea, with 25% of its volume filled with water. Then there is nothing to stop the whole module from spinning in any direction about its center of gravity. If we now divide this sphere into many little compartments and fill the lowest 25% of these with water then we essentially have a module that bears a close resemblance to a weeble in terms of mass distribution. Each time it is pushed from its stable position it will tend to return to this equilibrium point. This is called pendulum stability. For every subdivision we create inside the module we have a set of trade offs. With every division we tend to the ideal module with a fixed center of gravity, but its a case of diminishing returns since while initial divisions will have great effect as you keep adding more you will reduce the effect and add more mass to the structure, also cutting down usable buoyancy tank volume. This isn't very scientific but instinct tells me that the ideal number of subdivisions is between 3 and 5 giving us somewhere between 9 and 25 separate buoyancy tanks, but this will depend upon application.[1]

We will go through a worked example for the rough design of a cubic floating module.[1]

If we require a rectangular module that has a surface of 5 meters by 5 meters and can take a payload of 4 tons in addition to its own mass then we need to calculate the mass of the structure, the mass of the water inside the structure and how much water we need to displace to get it to float.[1]

The volume of the structure is given by the height x width x length for a rectangular object. We'll use the height as 3 meters for now, we can always go back and change it later.

This gives us a volume of 75m3.

If we assume that we will be using seacrete or concrete as a basis for the structure then the calculations are as follows. Steps will be similar but with different figures for other materials.

If we use a wall thickness of 0.1 meters then the volume of the walls is given by (height x width x thickness x 2) + (width x length x thickness x2) + (height x length x thickness x 2)


(3x5x0.1x2) + (5x5x0.1x2) + (3x5x0.1x2) = volume

      3       +      5      +      3       = 11m3

The mass of the walls will be given by volume of walls x density

If we use the mass of sea water as 1020kg/m3, air as 1kg/m3 and concrete as 2750kg/m3

For concrete this would be

11 x 2750kg/m3 = 30250kg

If we add to this the mass of air inside the structure we get an overall figure of 30325kg

The volume of water the structure will displace if fully submerged is 75m3 (The volume inside the structure) + 11m3 (The volume of the walls) for a total of 86m3 The mass of water it will displace is 86m3 x density of water

or 86m3 x 1020kg/m3 = 87720kg

Since this is greater than the mass of the structure it should float and should be able to take a payload of 57395kg before it would begin to sink. However unless you distributed the load carefully the structure is more likely to fail before you get to this point.

So far we have neglected to include subdivision of the tanks into the calculations. If we wish to calculate the extra mass required to subdivide the buoyancy tanks we do the following.

Decide how much we will subdivide then tank by.

For example to divide it into 9 sub-tanks we would require 4 extra panels. 2 in the lengthwise direction and 2 in the widthwise direction. Volume of these panels can be calculated as follows.

(w x h x thickness x #panels) + (l x h x thickness x #panels) = total additional volume.

for our example previously this would give an additional 6m3 of volume (which needs to also come off the usable volume of the tanks when filled with air) which has a mass of 6m3 x 2750kg/m3 = 16500kg

We can do this technique for more complex structures as long as the masses of the structure and water displaced is known or can be calculated.


There are many techniques used for anchoring items to the sea bed. The simplest technique is simply to drop a large mass onto the sea bed and tether an object to it. However, this solution is neither a particularly elegant solution nor is it efficient in terms of raw materials.

One technique, which has gained popularity with structural designers in recent years, is the idea of dropping a large bell onto the sea floor and pumping water from it. While water is being removed, the bell will fill with sand, either by sucking up a large mass of sand into itself, thereby causing its mass to increase, or by burying itself in the seabed, causing an increase in static friction of the anchor. Which condition occurs will depend upon the design of the anchor and the amount of suction provided upon installation. It is unknown whether the first situation would have long term durability.


The first step is to build a steel frame out of metal. (sources of metal can be rebar, thick gauge wire, tie wire, chicken wire, hardware cloth etc.) To create solid structures, the spacing between terminals should be kept to a minimum. (The reef structures currently being built feature spacing of half a foot or more) 1/4 to 1/2 inch might prove most advantageous for an island. Keep the anodes (positive terminal) around 4-6 inches away from the cathode (negative terminal) screen. the metal structure can be anchored in a shallow part of the ocean, powered by floating solar panels. Placing the anodes half a foot from the sides of the island the limestone will grow around the outside then later the insides will fill in. To increase the size, the anodes will be moved farther from the sides of the island.

Efficiency of Accretion
1.23 100
1.5 82
3 41
6 20.5
12 10.25
17 7.24



Plants are the most important part of a floating island as it will be extremely prone to erosion. You will have to make sure the plants you put on the island can grow in whatever environment you chose to put the island in. If you build your island in saltwater, you might need to use plants that can survive in environments that are rich in salt, such as mangrove trees. If you are growing plants that are not resistant to salt water, you need to make sure that the soil in which the plants are growing has no contact with the subterranean sea water. You might want to cover the bottom of the surface which is supporting the soil with either concrete or wooden boards.

Additionally, the roots of plants will add support and strength to the soil. Grass might be a good plant to start with, which will also improve the aesthetic condition of the island.



If you ever get to the point where you have successfully built an artificial island, it still will not be fit for human habitation without some necessities, listed below in descending order of importance:

Building on a floating island will create problems. The conventional way of having a few support posts anchored to to ground in a pool of cement simply will not work and you have to figure out how to disperse the weight of the building so it doesn't sink.

Moving a Floating Island


You could have a fleet of tugboats with cables attached to a sturdy part of your island tow it to another location.

If the design is modular the modules can be moved individually, in fact they could be linked in a long chain to minimize drag for travel over long distance and then rearranged on location.


Build a mast near the middle of your island so that you can use sails to drag your island to another location using wind. It's important that your mast is sturdy and large enough to catch enough wind to efficiently move your island, but not so big and heavy that its hard for your island to support it. Also, putting your sails too high might tip your island altogether in rough winds, so it is best to set it such that it is low enough not to let the island blow over (closer to the center of gravity), yet not so low that it gets in the way and/or is not able to catch enough wind. Making the bottom of your island more stream-line would help in reducing drag. This method should be more effective if your island is small.

  1. a b c d e f g h i "Apply Seasteading Concrete Shell Structures - The Seasteading Institute". The Seasteading Institute. Archived from the original on 2010-07-10.