Bathymetry

As on land there are hills and valleys on the seabed too. Bathymetry is the study of underwater depth of lake or ocean floors.

The shape of the seabed has a great influence on currents and therefore on the climate, the flora and fauna, the occurence of natural resources, the tides, tsunamis and of course on a ships safety at sea. Along the edges of tectonic plates huge trenches and ridges are formed.

It would be very interesting to display detailed bathymetry data on a free nautical map (e.g. OpenSeaMap.org). While for the deep sea a rather coarse resolution is sufficient, it is vital to have very detailed data for the shallow coastal waters.

For shoals see:Water Depth.

First steps

Maps of dry land

Map	Link	Equidistance	Shading
	opencyclemap.org	10 m
	topo.geofabrik.de	10 m	ja
	openpistemap.org	10 m
Slowakische Karte	freemap.sk	20 m	ja

Nautical Chart

Seekarte

OpenSeaMap.org

not jet...

Tobias Wendorff is computing a depth data model and rendering

Christoph Eckert computed the whole world in 1° tiles

A student of Frederik Ramm did something too.

Alexander Zipf computes Europe

in the OSM-Wiki

Contours of the Cyclemap

Relief-maps

HikingBikingMaps

Lowest Astronomical Tide (LAT) - as a base for water depths in costal waters

Tools

srtm2osm

Srtm2Osm: automatically downloads the data and converts it to OSM file format. One requests data within a bounding box , the resolution of the resulting data and it outputs an OSM file. This tool directly downloads SRTM3 V2 data. Caveats: Doesn't work with a proxy, the original data has enormeous artefacts within the bigger mountains, and it doesn't work with very large areas.

Links

SRTM all about SRTM data and the data itself

Global Bathymetric Prediction for Ocean Modelling and Marine Geophysics

Cleantopo2, edited SRTM30_plus data (land and sea data), public domain, full resolution, 16-bit tiff files, resolution 10.800 x 5.400 px.

NDGC: Coastal data for the US, Pacific and atlantic coast, Gulf of Mexico, public domain

CIGAR: SRTM to fill the gaps, according to Frederik Ramm not CC-BY-SA-compatible

collection of links

Rendering

All this has to be adapted to the certain areas of interest. In the Mediterranean, with a depth of about 4000 meters, the rendering has to be different from, say, the Baltic Sea with an average depth of 50 meters.

Details have to be shown in coastal waters at zomlevel 12 and above.

Bigger lakes should have depth lines too, at zoomlevel 13 or above.

For sailors, Fischermen and Divers

maximum detail in coastal waters where it is most interesting for sailors, fischermen and divers: