NL-DE sea territory

Dear mappers in the Netherlands,

as some of you may know the sea territory between the Netherlands and Germany is somewhat disputed.
Currently, the OSM boundaries of both country relations follow the Dutch view. Recently some mappers in Germany started mapping the official German view of the territory as nation-level boundary segments. You can already see it on the map as two separate borders.

The German OSM forum already discussed this issue and how it should be handled in OSM.
We agreed, that the Dutch OSM community must be included in the discussion.

Basically, we discussed two options:

  1. Each country is modelled in its own view (resulting in overlapping boundaries)
  2. We only map the undisputed areas (resulting in some undefined sea area that should be marked as disputed)

Let me also emphasize that we understand that this a complicated and sensitive topic. Unfortunately, politicians not yet resolved this rather technical question. For instance, Germany and Luxembourg agreed upon a shared territory for the water area of the rivers between both countries. But this area is much smaller and also not yet mapped in OSM.

Best regards

Hello Gehrke!

I see you’ve already found the talk-de thread of 2010 about this issue.

The German and Dutch governments agreed in August 2013 to hash out an agreement[1][2] about jurisdiction in this area. As it stands, an official agreement about the border may not be part of it, but who knows? As with everything in politics, it will surely take more time to finish the negotiations. I also wonder if they will ever come to an agreement. :slight_smile:

Personally, I now believe that mapping both interpretations of this border segment might be the wisest thing to do. Add a note to both sections explaining why there are currently 2 border segments there, and their source. If, by miracle, our governments come to an agreement about the border itself, we can adjust our mapping accordingly. My personal two cents.


  1. I wasn’t aware of any border dispute between Germany and The Netherlands till this thread, so it might create a nice public relations moment for OSM in both our countries showing the current rendering
  2. I agree with Ldp: leave both interpretations there as they are now, so please don’t split up relations 51477 and 47796
  3. Formally it’s the DWG who handles border disputes :smiley:

Cheers, Johan

ok. thanks for your feedback so far!

One other remark (also posted on the German forum):
Is OSM that robust that it can handle two administrative relations with the same level which overlap correctly? In other words: Can it break Nominatim? We are in the comfortable position that there are very few places in the disputed area, but if I would search for one of those, can OSM handle the request without breaking. It may choose one country at random, the first it sees in the database or it shows two hits. It shows for this isle ( the Netherlands, but the second border was added very recently and might not be present in Nominatim yet.

As a Dutchman who maintains the administrative boundaries, my vote is for option 1.

The boundary from the German perspective is based on an ancient agreement that doesn’t account for changes in international law since then (it discards the territorial sea of The Netherlands), the Dutch perspective includes this and places the boundary away from the shoreline.

Supporting both views within OSM seems the best option in the spirit of compromise. The OSMF Disputed Territories document mentions recording only one view, the most widely internationally recognised view:

If the tools don’t support overlapping national boundaries were we each use our own view on the border, we should be the ones to fix that so we can help with supporting alternative sets directly as also mentioned in the OSMF document.

I wouldn’t rely too much on Nominatim anyway. Nominatim is messing around with place nodes across boundaries in a way that, in my perspective, seems rather weird.

The national boundary of Germany is now according to the German interpretation. So far the national boundary of The Netherlands hasn’t been adapted to the German view. Let it stay that way, I like our authorative boundaries. :slight_smile: