1 · Executive Summary
Direct answer: No locations exist in international waters (>200 nm from any country), within 2,000 nm of Anguilla, that are <100 ft deep with sandy bottoms.
Qualifying international-water sites found: 0. Seastead capacity at those sites: 0.
This is not a gap in the research — it is a structural feature of ocean geography:
- Shallow water = national jurisdiction. Water <100 ft (<30 m) occurs almost exclusively on continental and island shelves. Every shelf in the Caribbean/Atlantic basin lies inside a 12-nm territorial sea or 200-nm EEZ.
- Even bare rocks create EEZs. Uninhabited islets (Sombrero, Aves, Sts. Peter & Paul) each generate a full 200-nm zone. There are no "jurisdiction holes" around shallow features.
- Open-ocean pinnacles are deep or distant. Seamount summits near Anguilla top out at 150–700 m depth. The world's shallowest truly remote bank (Gettysburg/Gorringe, ~25–30 m summit) is ~2,950 nm away, rocky, and subject to Portuguese extended-shelf and conservation interests.
The good news: your other goals — out of sight of residents, sandy bottom, <100 ft depth — are readily achievable inside Anguilla's own 12–200 nm zones, especially near the uninhabited islands of Dog and Sombrero. See §5.
2 · Why "Shallow International Water" Essentially Doesn't Exist
- Depth profile: The open Atlantic beyond the shelves is 3,000–5,500 m deep. The transition from shelf (<200 m) to abyss happens within tens of miles of land — always well inside a 200-nm EEZ.
- UNCLOS zoning tiles the map: Every piece of land — continent, island, or 1-hectare rock — projects a 12-nm territorial sea and a 200-nm EEZ. Adjacent states' zones abut; there are no gaps near coasts.
- The seabed beyond 200 nm ("the Area") is administered by the International Seabed Authority; there is no private-use framework for mooring to it, and in any case it is everywhere >2,000 m deep in this region.
- Extended continental shelves (CLCS submissions) can extend seabed jurisdiction past 200 nm for some states — making "international seabed" even rarer than "international water."
Average ocean depth ≈ 12,100 ft
<100 ft water ⇒ shelf ⇒ national jurisdiction
Rocks & islets ⇒ full 200-nm EEZ
High-seas seabed here: >6,500 ft deep
3 · Shallow Features Checked Within 2,000 nm of Anguilla
Every charted bank, reef, or seamount summit that plausibly could satisfy the depth criterion was evaluated. Positions are feature centers; distances are great-circle from central Anguilla (≈18.17°N, 63.06°W).
| Feature | Approx. center | Min. depth | Jurisdiction | Dist. / bearing from Anguilla | Why it fails |
|---|---|---|---|---|---|
| Saba Bank | 17.30°N, 63.40°W | 65–165 ft | Netherlands (Caribbean NL) | ~56 nm SW | Dutch EEZ (large sandy bank — ideal physically, wrong flag) |
| Aves Bank / Ridge | 15.67°N, 63.62°W | <20 ft (lagoon) | Venezuela (contested) | ~153 nm SSW | Claimed; disputed sovereignty |
| Navidad Bank | 19.90°N, 69.60°W | <30 ft | Dominican Republic | ~390 nm W | DR EEZ; humpback whale habitat |
| Silver Bank | 19.75°N, 70.05°W | <80 ft | Dominican Republic | ~413 nm W | DR EEZ; designated whale sanctuary |
| Mouchoir Bank | 21.15°N, 71.40°W | <60 ft | Turks & Caicos (UK) | ~507 nm WNW | TCI/UK fisheries zone |
| Hogsty Reef | 21.60°N, 73.83°W | <60 ft | Bahamas | ~647 nm WNW | Bahamian EEZ; atoll reserve |
| Bermuda Platform | 32.30°N, 64.75°W | <60 ft | UK (BOT) | ~853 nm N | Bermudan EEZ |
| Great Meteor Seamount | 30.00°N, 28.38°W | ~885 ft summit | High seas (seabed = Area) | ~2,030 nm NE | Summit far deeper than 100 ft; rocky |
| Hyères / Irving / Cruiser / Atlantis Seamounts | 29–33°N, 26–31°W | ~590–2,300 ft summits | High seas | ~1,900–2,300 nm NE | All too deep; rocky substrates |
| Gettysburg Seamount (Gorringe Bank) | 36.53°N, 11.53°W | ~80–100 ft summit | Portuguese extended-shelf / conservation interest | ~2,950 nm NE | Outside 2,000 nm; rocky; protected-area proposals |
| Banco de la Concepción | 28.88°N, 13.33°W | ~145 ft summit | Spain (Canaries) | ~2,950 nm ENE | Spanish EEZ; too deep; too far |
| Ampère Seamount | 35.08°N, 12.93°W | ~260–295 ft summit | Portugal/Morocco vicinity | ~3,050 nm NE | Too deep; too far |
| Sts. Peter & Paul Rocks | 0.92°N, 29.35°W | Islets + shelf | Brazil (+ ECS claim) | ~2,250 nm S | Brazilian EEZ; outside 2,000 nm |
| Rocas Atoll | 3.87°S, 33.83°W | <30 ft | Brazil (biological reserve) | ~2,200 nm S | Brazilian EEZ; strict reserve; outside 2,000 nm |
Result: 0 of 14 candidates satisfy all three criteria (high-seas + <100 ft + sand). The pattern is consistent: shallow ⇒ claimed; unclaimed ⇒ deep.
4 · Requested Results — International-Water Sites
| # | Location | Center lat/lon | Direction–distance from nearest country | Size of area | Seasteads @ 500-ft grid | Typical wave heights |
|---|---|---|---|---|---|---|
| — | None identified | n/a | n/a | n/a | 0 | n/a (regional open-ocean Hs ≈ 3–8 ft typical; hurricane extremes 30–45 ft — see §7) |
5 · Plan B — Out-of-Sight Sites Inside Anguilla's Own Waters
Your visibility goal does not require international waters. From beach-level eyes (~6 ft), the horizon is only ~2.9 nm; even from Crocus Hill (213 ft, the island's high point) it is ~17 nm. A structure 30–40 ft tall adds ~6–7 nm to its own visibility distance. Therefore anything ≳20–25 nm from Anguilla is below the horizon from every inhabited viewpoint — and the entire 12–200 nm ring is Anguillian territory, where permitting is straightforward compared to any foreign EEZ.
Candidate areas (all approximate — verify with charts & field survey)
| ID | Name | Approx. center | From Anguilla (Road Bay) | Est. depth | Bottom | Visibility from residents | Exposure / waves | Illustrative capacity* |
|---|---|---|---|---|---|---|---|---|
| A | Dog–Sombrero corridor | 18.585°N, 63.420°W | ~30 nm WNW (brg ≈ 309°) | ~25–60 ft? (verify — bank edge nearby) | Sand/rubble expected on bank; verify | Fully below horizon even from Crocus Hill (~30 nm); nearest humans = none (both islands uninhabited) | Partly leeched of N swell by Dog I.; open to E trade chop; Hs typ. 3–7 ft | ~650 units (7.5 sq nm usable) |
| B | West-bank roadstead (WSW of Road Bay, W of Prickly Pear) | 18.250°N, 63.350°W | ~16 nm W (brg ≈ 284°) | ~50–130 ft (verify) | Sand patches among reef — survey needed | Hidden from beaches; marginally visible from Crocus Hill (~16.5 nm vs 17 nm horizon) — shift 2 nm W to clear | Moderate; N swell wraps; Hs typ. 3–6 ft | ~330 units (3.75 sq nm usable) |
| C | SE bank rim (toward St-Barth median line) | 18.100°N, 62.900°W | ~10.5 nm ESE (brg ≈ 157°) | ~65–130 ft (verify) | Sand probable on bank | Below beach horizon (borderline for tall units); visible from Crocus Hill; near FR maritime boundary & yacht traffic | Open Atlantic swell; Hs typ. 4–8 ft | ~265 units (3.0 sq nm usable) |
*Illustrative maximums assuming the stated usable area at 60% layout efficiency on a 500-ft grid — pending bathymetric and benthic survey. Candidate A is the strongest: uninhabited surroundings, longest sight-line clearance, and simplest permitting story (still Anguillian waters).
Two honest cautions on "hiding":
(1) Visual discretion does not change the legal requirement — Anguilla (a UK Overseas Territory) requires planning/marine consent for offshore structures in its territorial sea, and under UNCLOS Art. 60 the coastal state authorizes installations in its EEZ regardless of who can see them.
(2) Safety marking is non-negotiable: once deployed, the structure must be charted (UKHO Notice to Mariners), lit/daymarked to IALA standards, and carry AIS. An unmarked obstruction in Caribbean waters is a serious collision-liability and insurance problem. "Invisible from shore" is fine; "invisible on charts" is not.
6 · Horizon & Visibility Math
Distance to horizon (nautical miles) ≈ 1.17 × √(height in feet) (includes standard refraction). A structure is hidden when the observer-to-structure distance exceeds observer horizon + structure horizon. Add ~10% margin for swell and non-standard refraction.
| Observer | Eye height | Horizon | + 35-ft seastead (horizon 6.9 nm) |
|---|---|---|---|
| Beach / small boat | 6 ft | 2.9 nm | hidden beyond ≈ 10 nm |
| Low-rise home | 20 ft | 5.2 nm | hidden beyond ≈ 12 nm |
| Hotel rooftop | 50 ft | 8.3 nm | hidden beyond ≈ 15 nm |
| Crocus Hill (island max) | 213 ft | 17.0 nm | hidden beyond ≈ 24 nm |
Practical rule: sites ≥ 25 nm from Anguilla are invisible from anywhere inhabited; sites ≥ 12 nm are invisible from all beaches. Candidate A (≈30 nm) clears every threshold.
7 · Grid Capacity Calculator (500-ft pitch)
Density reference: 1 sq nm = 36.92 million ft² → a 500 ft × 500 ft cell yields 147.7 theoretical units per sq nm (≈89/sq nm at 60% efficiency, allowing for buffers, swing rooms, and unusable patches).
8 · Wave Climate (≈18°N, 63°W — Anguilla Bank region)
| Season | Prevailing conditions | Typical significant wave height (Hs) | Episodes |
|---|---|---|---|
| Dec–Feb | ENE trades 15–20 kt; North-Atlantic swell windows | 5–8 ft | N/NW swell events 10–16 ft on north-facing coasts |
| Mar–May | E trades 12–18 kt | 4–6 ft | Late-season cold fronts, occasional N swell |
| Jun–Aug | ESE trades 10–15 kt | 3–5 ft | Tropical waves push 6–10 ft |
| Sep–Nov | Variable; hurricane peak | 4–6 ft | Hurricanes: Hs 25–45 ft, Hmax 60+ ft possible |
- Lee of Dog Island / south-bank sites typically run 30–50% lower than the open-bank figures above.
- Hurricane reality check: Anguilla lies in the core of the hurricane belt (Donna 1960, Lenny 1999, Irma 2017 — Cat 5, near-total island damage). A tension-leg platform sized for "normal Caribbean waves" will encounter 100-year design conditions of roughly Hs 35–45 ft and sustained winds 130–160 kt within its service life.
- Design implications: either engineer for the 100-year event (tendon loads, airgap, VIV, foundation pull-out capacity in sand), or adopt a storm strategy — e.g., detachable tendon heads with pre-storm demobilization, or a submersible/float-off mode. Mooring screws in sand have finite vertical pull-out capacity; verify against ultimate storm uplift, not operating load.
9 · Permitting, Safety & Environmental Checklist
- Anguilla Physical Planning — development consent for offshore/marine structures (territorial sea).
- Dept. of Fisheries & Marine Resources — marine parks/protected areas, benthic survey requirements; Dog, Scrub and Sombrero are seabird Important Bird Areas; Sombrero hosts an endemic lizard — maintain buffers.
- Seabed licence / Crown estate terms via the Governor's Office / Attorneys General chambers (UK OT process).
- EEZ installations (12–200 nm): coastal-state authorization per UNCLOS Art. 60; 500-m safety zone; structure must appear on charts.
- Hydrography: submit particulars to UKHO for Notice to Mariners; update Admiralty/NGA depictions.
- Navigation aids: IALA-compliant light(s), daymark, radar reflector, AIS transponder; monitor Anegada Passage traffic (major Europe–Panama lane) with historical AIS data before siting.
- Submarine cables: telecom cables land on Anguilla and cross the bank — obtain cable-route charts before any screw penetration; cable-fault liability is severe.
- Benthic verification: multibeam or satellite-derived bathymetry + drop-camera to confirm sand (not coral/rubble) at each screw location; seagrass avoidance.
- Insurance & classification: discuss with a marine insurer early — uncharted "fixed platform" status affects premiums more than wave height does.
10 · Verification Resources
- Bathymetry: GEBCO 2024 grid (gebco.net); British Admiralty & NGA charts of the Leeward Islands; Sentinel-2 satellite-derived bathymetry for the bank shallows.
- Waves: NOAA WaveWatch III hindcast/reanalysis; NHC Atlas of Pilot Charts, North Atlantic; buoy/altimeter climatologies.
- Jurisdiction: UN DOALOS EEZ/territorial-sea polygons (vliz.be/marregions); CLCS submissions for extended shelves.
- Traffic: historical AIS (MarineTraffic, EMODnet Human Activities).
- Cables: TeleGeography submarine cable map; ICPC recommendations.
- Local: Anguilla Government — Physical Planning Dept.; Fisheries & Marine Resources; UK FCDO (Overseas Territories).