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I always wondered where cartographers get their bathymetric data from to create maps like the Zanzibar map on wikipedia for instance. I could download polygons for the 1000 meter polygons on naturalearthdata.com but I want to show maximum 100 meter levels or lower. Thus the question: What ist the easiest, user-friendliest way? Like naturalearthdata, but in 100s...

There was a similar question asked in this forum, I tried the named sources, but I couldn't figure out where exactly to download and how to transform the format. Therefore I need a better description on HOW to download the data and convert it to an appropriate GIS format.

I work with ArcMap 10.4 or QGIS 2.16. A SRTM raster tile (geotiff) would be fine (like for the land areas) or Polygon/Line Featureclasses/Shapefiles.

enter image description here

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    Please list the links you have tried, specify what software you are using, your desired output. Cartographers often purchase data of this accuracy level, but there should be something out there for free – jbalk Sep 2 '16 at 5:34
  • I edited my question, you can find the information there. – Enzo Baldini Sep 2 '16 at 5:42
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    "There was a similar question asked in this forum, I tried the named sources" -- please add the links to the question you mentioned links to the 'named sources' you mentioned? We need to know what you are trying to download so we know how to deal with it. – jbalk Sep 2 '16 at 5:46
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    Do you have a particular area in mind? Can you use DBDB-V? I'd caution that bathy data is sometimes bogus (ancient, invented from sea level / gravity for most deep water, or just never measured). Unfortunately there was no SRTM equivalent for underwater. GEBCO might be usable: gebco.net/data_and_products/gridded_bathymetry_data - have you looked at that? – BradHards Sep 2 '16 at 5:55
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Another option you have is the ETOPO1 Global Relief Model. It has a 1-arc minute resolution (so slightly lower than the option above), but it comes in one complete file rather than 30 different tiles, so it may be easier to work with depending on what you are doing. It can also be downloaded as a georeferenced tiff that can easily be imported into ArcMap.

  • Thanks for the link. Maybe I am blind - but it would be great if you post the exact download-link. But that's exactly the problem I am facing browsing these nerdy scientify websites: I don't know where to click to download the data... Is it ngdc.noaa.gov/mgg/global/relief/ETOPO1/image and than color_etopo1_ice_full.tif.zip ?? – Enzo Baldini Sep 2 '16 at 11:18
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    Sure! This is the link you want: ngdc.noaa.gov/mgg/global/relief/ETOPO1/data/ice_surface/…. I get you over the nerdy websites. Even as a nerdy scientist I sometimes struggle to work out what I need to download! – Pete Sep 2 '16 at 13:06
  • Thanks for helping me to find the button. ;) Therefore it worked finally, thanks a lot! I get a 400 MB geotiff fo the whole world and I can show the bathymetry around islands for any place in the world. Or generate line or polygone featureclasses. For my cartographic needs its enough, I don't need higher resolution for analysis purposes. Thanks. – Enzo Baldini Sep 2 '16 at 14:34
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You can use SRTM30 PLUS which include topography and bathymetry of roughly 1km spatial resolution. The data covers the entire globe. You can choose the location you want. Also, the above link has multiple versions, please check the one you need, and there is an FTP link to download the data.

  • He asked for 100m resolution or less – jbalk Sep 2 '16 at 5:47
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    Why the down vote? He didn't say 100 m resolution. You need to read carefully. He asked for 100 m level or less in terms of depth not resolution. – ahmadhanb Sep 2 '16 at 5:51
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    You are correct. Apologies. I removed my downvote and gave you an upvote, as your answer is valid. – jbalk Sep 2 '16 at 5:52
  • Thanks a lot for the link. I will try and let you know whether it worked out. – Enzo Baldini Sep 2 '16 at 5:58
  • I downloaded all three different types (.nc, .sid, .srtm) and tried to import these files to ArcMap, but it didn't work out. I am not familiar with these file formats. I will work with the ETOPO1 Global Relief Model suggested by Pete. Thanks anyway. – Enzo Baldini Sep 3 '16 at 13:12
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Another source is the General Bathymetric Chart of the Oceans. Their 30-arc second dataset is (in my limited experience) better than the SRTM data for bathymetry because they use data from actual ship depth soundings for bathymetry where available.

  • I tried it twice, but the process of downloading, registration, etc. is too cimplicated for me ;) I will work with the file suggested by Pete, thanks anyway. – Enzo Baldini Sep 3 '16 at 13:14
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There is a bathymetry dataset for North America at Natural Resources Canada. Polygon and polyline shapefiles. Not exactly good enough for Enzo, but it might be useful for other people.

  The North American Atlas - Bathymetry data set shows the depth in metres for ocean 
  areas covered by the extent of the North American Atlas project.  Isobaths (lines of 
  equal depth) are provided for sea level (coastline, with depth = 1), 200, 500, and 
  2500 metres.  Polygons bounded by these isobaths represent depth ranges of 0-200, 
  201-500, 501-2500, and greater than 2500 metres.

Bathymetry screenshot

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