Please, read wiki about natural=coastline tag. You should be very careful when assigning it.

Please, use JOSM Validation plugin when editing coastlines.

Or add natural=water here relation/2186218

Please, use JOSM Validation plugin when editing coastlines.

Well, I reverted to the initial state (before your changes) because coastline validation failed (no 1-1 connection and direction - land on the left).

You can revert my revert and update coastlines correctly. Use JOSM Validation plugin.

Or you can add natural water here relation/2186110

You have deleted a bunch of natural=coastline. Please, use JOSM Editor with validator for coastlines.

Why place=country? It is "state", no?

I removed invalid coastline.
See duplicate islands, is it intended?
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1531630810

Be careful with natural=coastline tags. Use coastlines validator in JOSM.

Please, edit natural=coastline data using JOSM editor with built-in Validator. Read OSM wiki about coastlines.

Reverted because of broken coastlines. Please check your changes again and you can revert my revert with the fix.

Coastlines are broken after this change.
Please, read natural=coastline for the correct mapping.

Coastlines are broken. Please, read OSM wiki about the natural=coastline tag.

Coastlines are broken here.

Coastlines are broken here.

Please, read the OSM wiki about natural=coastline. It has a very strict use-case.

Please, read the OSM wiki about natural=coastline tag. It is incorrect to use it in the way you did in this changeset.

Revert this changeset because natural=coastlines are broken.

Please, read OSM wiki about coastlines and use JOSM editor + Validator where they are affected.

New coastline way/1449436936 duplicates the existing one way/1447932542

IDK, what should remain here (different roles in Relation).

You change breaks coastlines. Please, read Wiki about natural=coastline tag. Fixed here changeset/174265883

Your changeset is not good:
- Please, read the OSM Wiki about tags. natural=coastline is not suitable here
- Add type defining tags if the point ("Localita mercury") means something (hotel, shop, amenity, etc)