NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum

First I have a lot of learning to do in terms of mapping with polygons; lines and roads I'm good with, but anyway...

I'm seeing a lot of variation in the map just in my general area, San Juan, PR. I wanted to name a lagoon in the area but I quickly discovered it was actually two lagoons and then I discovered that the polygon was actually encompassing the outlets for the lagoons as well.

There are other water bodies in the area that I've noticed are not polygons but are named using points and their shorelines are marked with the NOAA U.S. Vector Shoreline. The lagoons I spoke of are also marked with the NOAA U.S. Vector Shoreline.

So I have a few questions.

If the shoreline is marked then is there a need to create an area with the natural=water tag? Is it best practice to create an area of water and then name it or to drop a point with a name in the middle of it?

Also, the outlets for the lagoons in question lead to a bridge and the polygon stops there at the bridge but I'd like to connect the water bodies under the bridge since they are continuous and navigable. Is this something that could or should be done?

If you'd like to see the area I'm talking about it is San Juan, Puerto Rico. Laguna San José and Laguna Los Corozos is the natural=water area and the Bahía San Juan is the unconnected water body.

asked 05 Jun '13, 15:55

EGhost57's gravatar image

accept rate: 0%

edited 05 Jun '13, 22:59

Usually nodes are used for water bodies when there is not enough data available to draw at least a rough outline of waterbody or the mapper does not have time to draw it. So if you have time and somekind of imagery or gps data for waterbody then map it as area not node.

One of the two lagoons had a redundant natural=water key on the outer shoreline because this key already existed in the relation. I Removed it.

All shorelines of sea are tagged as natural=coastline and these ways must be connected to each other.

You can map bays as

  • separate areas
  • multipolygons and therefore reusing the existing coastline way (+ you need to make one new way to connect endpoints of the existing coastline way.).
  • points in the middle of bay

You can read more about tagging of bays in the wiki.

If there is water under these bridges then you may connect these water areas or create a line with waterway='something' between them dependenig on the real situation on the ground.

permanent link
This answer is marked "community wiki".

answered 05 Jun '13, 17:34

RM87's gravatar image

accept rate: 22%


Thanks for the speedy reply. I've experimented with some smaller stuff and I think I'm getting the hang of it. I even found an island that was flooded (by poor tagging) in the middle of a small lake.

I think I might try my hand at creating those lagoons and San Juan Bay.

Thanks again!

(05 Jun '13, 19:18) EGhost57

Please, be careful when removing "natural=water" objects related to the coastline (and lake, and river) objects. There are thousands of similar cases and these are NOT redundant (though, logically questionable, formally in accordance with OSM Wiki documentation). This way local editors try to fine-tune sections of a water area borderlines. The logic behind these kind of editing/correction is understandable. It is easier and with no risk to make damage to large objects like a continent border and so on.

(06 Jun '13, 07:56) sanser

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here



Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text]( "title")
  • image?![alt text](/path/img.jpg "title")
  • numbered list: 1. Foo 2. Bar
  • to add a line break simply add two spaces to where you would like the new line to be.
  • basic HTML tags are also supported

Question tags:


question asked: 05 Jun '13, 15:55

question was seen: 6,599 times

last updated: 06 Jun '13, 07:56

NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum