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Public-images-osm logo.svg place = sea
Envisat image over the Red Sea ESA209860.jpg
A part of an ocean. Edit or translate this description.
Group: Places
Used on these elements
may be used on nodesshould not be used on waysmay be used on areasshould not be used on relations
Useful combination
Status: proposedPage for proposal


A large body of marine water and part of an ocean: seas, gulfs such as the Gulf of Mexico, bights and very large bays such as the Bay of Biscay and Bay of Bengal.

Note that oceans are mapped separately, see place=ocean.

How to Map

Add the place=sea to a node near the center of the marine water body.


Simple example:

name=South China Sea

Or you can expand with more information and the name in other languages to help searching:

name=South China Sea
is_in:ocean=Pacific Ocean

Mapping seas as areas

Originally most seas (including large bays and gulf, such as the Gulf of Mexico and the Bay of Bengal) were mapped as nodes in late 2008: there were about 110 at that time. In 2014 and 2015 about a dozen additional seas were mapped as multipolygon relations. In late 2018 and early 2019, a number of sea nodes were deleted and large multipolygons were created instead. This is controversial, because most seas do not have verifiable boundaries with the open ocean or other seas. Also, such large multipolygon relations can be very difficult to maintain; they must be edited whenever the coastline is split or merged or a new island is created, and thus can be easily broken. For these reasons mapping seas as areas with multipolygons is controversial.

Note that oceans are always mapped as nodes, and most bays are mapped as nodes (There are 47,000 bay nodes vs 7,000 bay ways and relations as of mid 2019).

The trend to map seas as multipolgyons is related to the increase in mapping bays and straits as multipolygons, which also became more common at the same time, most likely due to a controversial change in rendering by the Openstreetmap-carto style sheet, the style used by the standard map layer on openstreetmap.org. However, note that seas are not rendered by that style as of mid-2019.

See also