Sounder

--

scroll to zoom / drag to pan / click for depth

API Docs

Sounder API

Depth estimation from Navionics nautical chart tile color analysis. Returns approximate water depth for any coordinate worldwide.

Endpoint

GET https://sounder.windward.parts/?lat={lat}&lon={lon}

Parameters

Param	Type	Description
lat	float	Latitude (-90 to 90)
lon	float	Longitude (-180 to 180)

Response

Copy{
  "depth": 14.2,     // meters, 0 for land, -1 for >100m
  "seabed": "unknown",
  "isLand": false,
  "isWater": true,
  "source": "ocr"    // "ocr" = precise sounding, "color" = estimated
}

Depth values

Value	Meaning
0	Land or intertidal zone
1 - 100	Estimated depth in meters
-1	Deep water (>100m, unshaded on chart)

Example: cURL

Copycurl "https://sounder.windward.parts/?lat=12.48&lon=-61.45"

Example: JavaScript

Copyasync function getDepth(lat, lon) {
  const res = await fetch(
    `https://sounder.windward.parts/?lat=${lat}&lon=${lon}`
  );
  return res.json();
}

// Usage
const data = await getDepth(12.48, -61.45);
console.log(data.depth, data.isLand);

Example: Python

Copyimport requests

def get_depth(lat, lon):
    r = requests.get(
        "https://sounder.windward.parts/",
        params={"lat": lat, "lon": lon}
    )
    return r.json()

# Usage
data = get_depth(12.48, -61.45)
print(f"Depth: {data['depth']}m, Land: {data['isLand']}")

Example: Batch query (Python)

Copyimport requests
from concurrent.futures import ThreadPoolExecutor

points = [
    (12.48, -61.45),   # Carriacou
    (12.44, -61.43),   # South of Carriacou
    (12.50, -61.48),   # West coast
]

def query(coord):
    lat, lon = coord
    r = requests.get(
        "https://sounder.windward.parts/",
        params={"lat": lat, "lon": lon}
    )
    return {**r.json(), "lat": lat, "lon": lon}

with ThreadPoolExecutor(max_workers=5) as pool:
    results = list(pool.map(query, points))

for r in results:
    print(f"({r['lat']}, {r['lon']}): {r['depth']}m")

Notes

Depth is estimated from Navionics chart tile colors at zoom level 14. Accuracy depends on chart coverage and color band resolution. Best for relative depth comparison rather than precise navigation.

Rate limiting: None currently. Tiles are cached server-side. Please be reasonable with batch queries.