Guide

What a Private Island Really Costs

The purchase price is the figure everyone quotes and the least important one in the file. The real cost of an island is what it takes to make it habitable and to keep it that way, year after year, against the sea.

There is a comfortable fiction in island buying that the hard part is finding the money for the purchase. In our experience the purchase is where the spending begins, not where it peaks. An undeveloped island bought for a modest sum can absorb several times its price before a single guest sleeps there, and then quietly demand a six-figure sum every year simply to stay as it is. This guide sets out the whole cost picture, in concrete ranges, so that the number you plan around is the real one.

Treat every figure here as illustrative rather than a quotation. Costs vary enormously with region, remoteness, ambition and the state of the market. But the shape of the spending is consistent, and understanding the shape is what stops a project running out of money halfway through the water plant.

Purchase price, by region

The entry point for a genuinely private island, small and undeveloped, in a jurisdiction that permits foreign ownership, is lower than most people expect. It is the location, the tenure and the development that carry the cost. The ranges below are broad and reflect what changes hands rather than what is optimistically listed.

The two ends of each range are almost different products. A quarter-million-dollar island is typically a few hectares of rock and scrub with no services and a difficult landing; a prime island at the top of the range comes with a jetty, plant, staff quarters and a licence to operate. Our regional notes on the Caribbean and the Indian Ocean break the geography down further, and the Bahamas and Fiji guides go deeper still on tenure.

The purchase is where the spending begins, not where it peaks.

The capital works nobody prices in

Between buying an island and living on it lies a body of infrastructure work that routinely costs more than the land. The mainland assumes water in the tap, power in the socket and a road to the door. An island assumes none of it, and building each system offshore carries a premium of anywhere from thirty per cent to well over double mainland cost, driven by the expense of moving people, plant and materials across water.

Water

Fresh water is the first problem and often the largest single line. Options are rainwater harvesting into tanks, a well if the geology gives you a lens of fresh groundwater, barged-in supply, or desalination. A rainwater-and-tank system for a household might run $30,000 to $140,000 installed. A reverse-osmosis desalination plant sized for a small resort commonly lands between $150,000 and $600,000, and it then draws power and demands maintenance for as long as it runs. Our dedicated guide on island water supply works through the choice in detail.

Power

Few private islands sit within reach of a grid cable, so power is generated on site. A diesel generator set is the cheapest to install and the most expensive to run and refuel. A solar array with battery storage costs more up front but transforms the running numbers and the noise. A hybrid of the two is now the norm. Budget roughly $100,000 to $500,000 for a household-scale system, and several times that for a resort. The power and energy guide sets out the trade-offs.

Jetty, access and marine works

A safe landing is not optional, and marine construction is punishing. A simple timber jetty in sheltered water might cost $50,000 to $200,000; a concrete jetty able to take a supply barge in exposed conditions can run from $300,000 into the millions. Dredging an approach channel, where permitted at all, is its own major project. Our note on access and transport covers landings, vessels and the helicopter question.

Building offshore

Construction itself carries the offshore premium in full. Every bag of cement, every tradesperson and every window arrives by boat, and weather stops work. As a rule of thumb, expect to pay one and a half to three times the equivalent mainland build cost, and to allow generously for programme, because an island build overruns more often than not. The building on a private island guide treats this properly.

A worked annual budget

Once built, an island costs money every year whether you visit or not. The figure that surprises new owners most is the running cost of a modest private retreat, not a resort. The table below is an illustrative annual operating budget for a small, staffed private island retreat, of the kind a family might use for part of the year. Treat it as a shape to test your own numbers against, not a quotation.

A useful planning discipline is to assume annual running costs of roughly two to five per cent of the all-in developed value of the island. A property worth ten million dollars developed will rarely cost less than two hundred thousand a year to keep, and often considerably more once staff and insurance are realistic. A resort, of course, is a different animal again, with a payroll and a marketing budget, and its economics belong in the income and resorts guide.

Assume annual running costs of two to five per cent of the developed value. An island is a standing expense, not a dormant asset.

The cost lines that vary most

Staffing

People are usually the largest running line and the hardest to get right. A single live-in caretaker keeps a place from decaying; a functioning household needs more. Remoteness raises wages, because you are paying for isolation as well as skill, and you are often housing and feeding staff as well as paying them. The staffing guide addresses recruitment, housing and the delicate matter of turnover on a small island.

Insurance and resilience

Island insurance is expensive and, in some hurricane and cyclone belts, increasingly hard to obtain at any price. Premiums are driven by wind and storm-surge exposure, by the quality of construction, and by how far you sit from help. Building to a high wind standard costs more up front and pays for itself in both premium and survival. Our insurance and resilience guide is worth reading before you commit to a hurricane-belt purchase, because the annual figure can move the whole economics of a project.

Hidden and one-off costs

• Transfer taxes and stamp duty, commonly 1–10% of the purchase price
• Legal, survey and diligence fees, often $30,000–$150,000 for a cross-border deal
• Foreign-ownership application and licensing fees
• Environmental and building permits, sometimes requiring paid studies
• The cost of a wasted viewing trip that a desk screen would have prevented
• Contingency: allow 15–25% on any offshore build programme

Putting the numbers together

A candid all-in picture for an undeveloped island taken to a comfortable private standard might read: purchase of one to three million, capital works of two to five million, and running costs of a quarter to half a million a year thereafter. The purchase, in other words, is frequently the smallest of the three. The projects that fail are the ones that budgeted for the first number and discovered the other two too late.

The way to avoid that is to price the whole thing before you offer, using the buying process to sequence the work and the due-diligence checklist to test every assumption. When you are ready to put real figures against a real property, the office can help you build a costed brief. Begin with the directory, or write to us directly.

General orientation, not legal or tax advice. Enquiries: the enquiry form.