sounding the seafloor

Palau National Marine Sanctuary

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Depth under cursor—

0 mreef · shelf · slope · trench7,208 m

Viewpoint 7.30°N · 134.40°E Palau · Western Pacific

Depth · 0 to 7,208 m

Reef flat0–5 m

Reef slope5–30

Mesophotic30–150

Shelf break150–200

Slope200–1,800

Abyssal1,800–5,000

Palau Trench5,000 m +

Maritime zones

Territorial sea12 nm

EEZ200 nm

Depth bands are ecological, not evenly spaced — they mark the reef-building limit, the mesophotic floor and the shelf break. Vertical scale is non-linear: the top 60 m is shown at full scale and everything below is compressed, or a 7 km trench would flatten the reef to a sheet. Seafloor provenance: 78% of this frame comes from GMRT's high-resolution multibeam soundings; the rest is interpolated from a coarser background grid and is measurably smoother. The closer views sit largely on that fill — Rock Islands 18% surveyed, Ulong Channel 2% — so fine structure there is the model, not a survey. Depths are relative to approximately mean sea level with no tidal reduction, so the waterline on a shallow flat is datum-dependent.

Reef structuretap a species ↗

Geomorphic zone

Lagoon

Reef flat

Back reef

Reef hole

Reef crest

Bank / shelf

Channel

Fore reef

Shoreline intertidal

Dredged

Vertical wall

Bank / shelf escarpment

Bottom cover

Live coral

Turf

No cover

Macroalgae

Unclassified

Seagrass

Emergent vegetation

Coralline algae

NOAA NCCOS benthic habitat mapping (CC0 1.0), photo-interpreted from orthoimagery. Zone and Biological Cover classes as NCCOS publishes them. Outside the mapped survey the class is unmapped, not absent, and “unclassified” means the survey could not call it — neither is a habitat.

Mangrove

Extent

Mangrove25 m

Extent change · live

1996 → 2016—

Clearing alerts, 90 d—

Global Forest Watch · loading

Global Mangrove Watch (Bunting et al.), ALOS PALSAR + Landsat. 205 patches intersect this frame, 58 km² by the dataset's own geometry — measured from the source polygons, not from this raster, because rasterising a thin coastal fringe over-reports its area by about a quarter. EXTENT only: not condition, not species, not canopy height.

Live · reef condition

Heat stress—

Sea surface temp—

vs. normal for here—

Bleaching alert—

Surface current—

NOAA Coral Reef Watch

Current is the ~25 km geostrophic field from altimetry — the regional set. It does not resolve tidal flow through a reef channel, which is the flow a diver feels and the flow that times a spawning aggregation.

10 km

Palau

The boundary · the record

Palau National Marine Sanctuary

One of the largest marine protected areas in the world, declared over a national exclusive economic zone of 619,959 km² — an ocean area roughly the size of France, held by a nation whose land area is 459 km².

EEZ: 619,959 km² Palau's UN deposit
No-take: 80 % of the EEZ
Territorial sea: 89,722 km² 12 nm, with internal waters
Deepest: 7,208 m Palau Trench
Highest: 242 m Ngerchelchuus

Palau National Marine Sanctuary Act — enacted 2015, fully in force 2020
Rock Islands Southern Lagoon — UNESCO World Heritage, inscribed 2012
Vertical relief of 7.4 km from the trench floor to Ngerchelchuus — more than the Annapurna frame in Landseed's terrestrial series, and all but 242 m of it underwater.
No sanctuary polygon is drawn. Neither OpenStreetMap nor any open inventory publishes the Palau National Marine Sanctuary boundary, and a maritime zone is not a protected area. The lines on this map are jurisdictional limits; the 80 % figure is statutory text, not a shape we can show you.

The 200 nm zone is drawn from the Republic of Palau's own deposit with the UN Secretary-General under UNCLOS Art. 75(2) (M.Z.N.62.2008.LOS) — the six deposited segments, reassembled here into one closed ring. Its outer limit is a true 200 nm arc only where it faces open ocean; where it meets a neighbour's zone it is a median line, agreed with the Federated States of Micronesia by treaty and claimed against Indonesia and the Philippines. That is why no distance alone reproduces this shape. The 12 nm line is OpenStreetMap's national boundary (ODbL). Palau has no OpenStreetMap protected-area polygon, so no OSM outline is claimed here. Bathymetry: GMRT synthesis (MGDS/Lamont-Doherty) at ~61 m; land elevation composited from AWS Terrain Tiles (SRTM) because GMRT's land component reported a 1,144 m peak in a country whose high point is 242 m. Reef classification: NOAA NCCOS benthic habitat mapping, CC0 1.0 (worldwide waiver). Note: the 80 % no-take figure is the statutory designation, not a measured compliance rate — those are different claims and this map does not assert the second.

Tree-cover loss 2024 Hansen GFC · all tree cover; 7% of it falls on mangrove

Bathymetry: GMRT (Ryan et al. 2009) · Land elevation: AWS Terrain Tiles · Imagery: contains modified Copernicus Sentinel data (2023-2025) · Reef classes: NOAA NCCOS benthic habitat mapping (CC0 1.0) · Maritime limits: Republic of Palau, deposited with the UN Secretary-General (M.Z.N.62.2008.LOS) · 12 nm line: OpenStreetMap (ODbL) · Coastlines: OpenStreetMap (ODbL) · Heat stress: NOAA Coral Reef Watch · An independent visualization — credits identify data provenance and imply no endorsement of, or affiliation with, this site by any provider · An independent visualization by Landseed PBC. Not affiliated with, endorsed by, or produced for any agency or organisation named here. · Globe texture: NASA