Guide

The Complete Private-Island Due-Diligence Checklist

Diligence is where an island purchase is won or lost. Done in the right order it protects your money and your patience; done carelessly it turns a dream into a standing liability. This is the full checklist, section by section.

An island hides its problems below the waterline, in the land registry and in the small print of a foreshore boundary. The photographs are always good; the questions that matter are the ones a photograph cannot answer. This guide sets out the complete diligence a serious buyer should run before completion, arranged so that the cheapest and most fatal enquiries come first. It is orientation, not legal advice, and every jurisdiction adds its own wrinkles, but the framework travels.

We structure diligence the way the Island Dossier structures a property record: one section at a time, each with a clear question and a clear answer, so that nothing is assumed and nothing is skipped. Work down the list, and let any red flag stop the process until it is resolved.

1. Title and tenure

Everything begins here, and if it fails, nothing else matters. The question is simple: does the seller own what they are selling, and can they convey it to you cleanly? The answer is often less simple than the seller believes.

• Registered title confirmed at the land registry in the seller's name
• The nature of tenure established: freehold, leasehold, or customary
• Full chain of title traced back far enough to be safe
• All mortgages, charges and liens identified and discharge arranged
• Boundaries on the title matched to the physical island
• Title held in a company whose ownership cannot be verified
• Unregistered land, or title based only on long possession
• Any live boundary or ownership dispute, however minor it is made to sound
• A leasehold with fewer years remaining than the seller emphasises

Where tenure is leasehold, the lease is the asset, and it must be read in full. A short residual term, an unfavourable renewal clause or a ground rent that ratchets can gut the value of an otherwise perfect island. The distinction is explored in the leasehold question, and it deserves your full attention before you spend a penny on survey.

The photographs are always good. The questions that matter are the ones a photograph cannot answer.

2. Foreshore, seabed and the water's edge

On the mainland the edge of your land is a fence. On an island it is a moving line of water, and who owns the strip between high and low tide, and the seabed beyond, is one of the most misunderstood questions in island buying. In many jurisdictions the Crown or the state owns the foreshore and the seabed, meaning you may own the island but not the beach, and certainly not the water your jetty stands in.

• The legal boundary of your ownership relative to the tide line established
• Ownership of the foreshore and any adjoining seabed confirmed
• Existing seabed leases or licences for jetties and moorings identified and transferable
• Public rights of access over the foreshore understood
• A jetty or building that sits on foreshore the seller does not control
• No seabed lease in place for existing marine structures
• A public right of landing that undermines the island's privacy

3. Physical survey and coastal dynamics

Now, and only now, does it become worth spending on physical survey. The land itself must be measured and understood: its elevation, its stability, and its behaviour under the sea's long pressure. Our field note on reading the water covers what to look for; the formal survey confirms it.

• Topographic survey establishing usable building platforms above spring high water
• Elevation and freeboard assessed against storm surge and sea-level projections
• Evidence of erosion or accretion over time, from historic imagery where possible
• Ground conditions tested for foundations and for a septic field
• Reef, sandbar and channel mapped by bathymetric survey
• Low elevation with no defensible high ground in a surge zone
• Active erosion on the side you intended to build on
• Ground that will not take a foundation or a soakaway without major expense

4. Access and transport

An island you cannot reliably reach, in the weather you will actually face, is a liability whatever its beauty. Access diligence tests the routes in and out for people, supplies and emergencies.

• Safe landing confirmed at the states of tide and weather you will use
• Reliable anchorage or mooring in prevailing and storm winds
• Distance and journey time to the nearest freight point and airport measured
• Emergency evacuation route to a Category A hospital established
• Any legal right of way over neighbouring water or land secured
• A landing usable only at high tide or in calm weather
• No practical means of medical evacuation after dark

The wider question of vessels, helicopters and resupply logistics is covered in access and transport.

5. Utilities and services

Assume nothing arrives by pipe or cable. Diligence must establish what services exist, what they cost to run, and what it will cost to provide those that do not.

The dedicated guides on water supply and power and energy set out how to test each system and what replacement or upgrade would cost.

6. Permits, planning and environment

What you may do with an island is often more constrained than what you may buy. Coastal-zone regulation, protected-area status and building consent all shape, and sometimes prohibit, development. Establish the envelope before you complete, not after.

• Zoning and permitted use for your intended purpose confirmed
• Building-consent regime and likely conditions understood
• Any protected-area, marine-park or heritage designation identified
• Environmental-impact requirements for your plans scoped
• Existing structures confirmed as lawfully permitted, not unauthorised
• Height, density and setback rules from the coastline established
• Existing buildings that lack permits and may face enforcement
• A protected designation that forbids the development you intend
• A commercial ambition in a jurisdiction that licenses tourism tightly

If your plans involve building, read this alongside the building guide, which treats permitting and the offshore construction premium in depth.

7. Valuation and market

Only once you know what you are buying can you judge whether the price is fair. Island valuation is an art, because comparables are scarce and each property is singular, but the discipline is worth applying rather than trusting the asking figure.

• Independent valuation obtained where the sum justifies it
• Recent comparable transactions in the region gathered, not just listings
• The cost to develop to your standard added to the purchase in your appraisal
• Resale liquidity considered honestly, as island markets are thin
• A price justified only by optimistic listings that never sold
• A property so specialised that resale would be very slow

Our full cost framework sits in what a private island really costs, and the disciplined approach to appraisal is set out in the acquisition brief.

8. Insurance and resilience

An island that cannot be insured, or can be insured only at a punishing premium, is a different proposition from one that can. Test insurability during diligence, not after completion, because the answer can change the whole economics.

• Availability of buildings and liability cover confirmed with a broker
• Indicative premium obtained against the actual construction and location
• Wind, flood and storm-surge exposure assessed
• Construction standard checked against what insurers require
• No insurer willing to write cover in that hurricane or cyclone belt
• A premium so high it undermines the running budget

The insurance and resilience guide goes further into building standards and self-insurance.

9. Structuring, approvals and completion

The final section confirms that the deal can actually close in the form you intend, cleanly and with your ownership properly recorded.

• Foreign-ownership consent obtainable, and its timeline understood
• Holding structure agreed with tax and legal advisers before completion
• Deposit and balance to move through regulated escrow only
• Stamp duty, transfer tax and registration fees quantified
• Registration process and responsibility for lodging the deed agreed
• A seller who resists escrow or asks for funds direct
• An assurance that foreign-ownership approval is a mere formality, unbacked by writing
• Pressure to complete before diligence is finished

That last flag is worth dwelling on. Urgency is the oldest lever in property, and on an island, where the buyer is remote and the diligence slow, it is used often. A genuine seller will let you finish the work. The buying process guide sets the whole sequence in context, and the quiet market note explains why patient, well-prepared buyers are the ones who are trusted with the better properties.

Urgency is the oldest lever in property. A genuine seller will let you finish the work.

Using the checklist

Print it, work it top to bottom, and treat every red flag as a stop rather than a footnote. Most flags can be resolved; the danger is not that they exist but that they go unexamined. When a section clears, record the answer in the same disciplined way the Island Dossier records a property, so that by completion you hold a full and orderly file rather than a folder of hopes.

If you would like the office to run or review diligence on a specific island, or to prepare a dossier before you view, write to us. You can also explore current opportunities in the directory, or, if you own an island and are weighing a discreet sale, register an island with us directly.

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