Lone diver descending toward a barely visible underwater structure — a beam of light from above, human scale against the ocean's immensity

The Expedition

The only step left is fieldwork.

Twelve criteria validated from desk research. Three require physical investigation. GEBCO Hill lies at diving depth, in a known sea, at precise coordinates.

7.522°N
Latitude
117.677°E
Longitude
−19 m
Summit depth
Sulu Sea
Philippines

GEBCO Hill: an underwater hill at recreational diving depth.

Coordinates 7.52245°N, 117.67676°E
Summit depth −19.2 m (standard recreational dive)
Elevation at LGM +101 m above sea level
Morphology Elliptical hill, ~5 km E-W × ~7 km N-S, base at −65 m
Concentric rings RMSE 6.2 m (6 params, Attic stade 185 m)
Body of water Sulu Sea, between Palawan and Sabah (Borneo)
Nearest port Brooke's Point, Palawan (~95 km)
Nearest airport Puerto Princesa (PPS), Palawan
Detection sources GEBCO 2024, GMRT v4.2, ETOPO 2022, satellite altimetry
UNESCO compliance Convention on the Protection of Underwater Cultural Heritage (2001)

GEBCO Hill is a submarine elevation in the Sulu Sea, detected by satellite altimetry and confirmed across four independent bathymetric datasets. Its summit lies at just 19 metres below the surface, within standard recreational diving range.

At the Last Glacial Maximum (~21,000 BP), this hill stood over 100 metres above sea level, at the centre of a vast emerged continental shelf connecting Borneo to Palawan. The surrounding plain, now at −83 m, was submerged around 12,650 BCE. GEBCO Hill survived as a residual island for approximately 3,000 more years before the rising waters covered it entirely.

Its radial profile matches Plato's concentric ring dimensions with an RMSE of 6.2 metres across six independent parameters. No parameter was optimised. The standard Attic stade of 185 m was applied throughout.

Scroll to zoom · Click markers for details · Basemap: ESRI Ocean · Data: GEBCO 2024

0 m
Sea surface
−19 m
GEBCO Hill summit
−40 m
Technical dive limit
−83 m
Deep zone (plain)
−120 m
LGM shoreline
14
Days in the field
Mar–Jun
Optimal window (dry season)
~70%
Detection probability if present

Three phases. Fourteen days. One answer.

From sonar mapping to direct visual inspection. Each phase informs the next. Negative results are published with the same rigour as positive ones.

01 Sonar Mapping Days 1–5

High-resolution acoustic survey of the entire GEBCO Hill structure and surrounding plateau. The goal: produce the first sub-metre bathymetric map of the site.

  • Multi-beam echo sounder survey (<5 m resolution)
  • Side-scan sonar for surface texture mapping
  • Sub-bottom profiler for sediment stratigraphy
  • Identify geometric patterns, concentric structures, canal traces
  • Map the summit dome and ring boundaries

Equipment

Multi-beam sonar, side-scan sonar, sub-bottom profiler, DGPS, data processing workstation

02 ROV Deep Survey Days 6–9

Remotely operated vehicle investigation of the deep zone (−83 m) where the ancient plain and canal network are predicted. Too deep for scuba, ideal for ROV.

  • Video transects of predicted canal alignments (az 44.5°)
  • Close inspection of sonar anomalies from Phase 1
  • Sediment sampling at key points (grab sampler)
  • Search for worked stone, anthropic material, anomalous deposits
  • Document the shelf edge (αποτομος) morphology

Equipment

ROV rated to 150 m, HD/4K camera, LED lighting, grab sampler, acoustic positioning

03 Targeted Diving Days 10–14

Direct human investigation of GEBCO Hill summit. At −19 m, the site is within standard recreational diving limits. This is where Plato's acropolis is predicted.

  • Visual inspection of the summit dome (central island zone)
  • Photogrammetric documentation of ring boundaries
  • Search for worked stone, tool marks, carved surfaces
  • Rock sampling for petrographic analysis
  • GPS-tagged photo/video documentation of all findings

Equipment

Standard scuba, underwater cameras, photogrammetry rig, sample bags, dive computers, surface comms

Four tiers of discovery. Even Bronze advances science.

🥉

Bronze

Complete high-resolution bathymetric map of GEBCO Hill. First sub-metre survey of the site. Confirms or refutes concentric ring structure. Scientific value regardless of archaeological outcome.

🥈

Silver

Geometric anomalies detected. Non-natural patterns, linear features, or concentric structures confirmed by sonar at resolution unavailable from satellite data.

🥇

Gold

Datable artefacts recovered. Worked stone, anthropic deposits, or material culture from the summit or deep zone. Establishes human presence at the site.

💠

Platinum

Pre-Holocene structures confirmed. Engineered features predating 9,600 BCE, consistent with H₃ predictions. This would rewrite the archaeological timeline.

A negative result at Bronze level already constitutes a definitive test. The expedition produces scientific value at every tier.

Science, not spectacle.

📖

Publish everything

All results published under CC-BY 4.0, positive or negative. Raw data, survey logs, dive reports, and sample analysis. No selective reporting.

🛡

UNESCO compliance

Full compliance with the UNESCO Convention on Underwater Cultural Heritage (2001). No disturbance beyond minimal sampling. In situ preservation prioritised.

🔄

Accept refutation

If the expedition returns negative results, we publish them and formally update our probability assessments. H₃ at GEBCO Hill would be refuted. We move on.

This investigation needs allies.

We are looking for researchers, institutions, divers, and partners who share our commitment to rigorous, open investigation.

Researchers & Institutions

Academic Collaboration

Marine archaeologists, geologists, bathymetric specialists, philologists, population geneticists. We are seeking institutional partnerships for peer review, co-authorship, and fieldwork participation.

Contact the Team

Dive Professionals

Expedition Crew

Certified dive masters, ROV operators, sonar technicians, underwater photographers with experience in tropical waters. The site is at −19 m, within standard recreational limits.

Apply to Join

Media & Documentary

Tell the Story

We are exploring partnerships with documentary producers and science journalists. The investigation, from Bayesian methodology to underwater fieldwork, is a story worth telling.

Media Enquiries

The investigation began with a question.
It produced coordinates, a methodology, and a site at diving depth.
The only step left is to go and look.

Fourteen days. Nineteen thousand euros. One answer.


Don't believe us. Check our data. Then help us check the seafloor.