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Public-images-osm logo.svg natural = bay
Lowlandman's Bay, Jura - geograph.org.uk - 25388.jpg
An area of water mostly surrounded by land but with level connection to the ocean or a lake. Edit or translate this description.
Group: Natural
Used on these elements
may be used on nodesmay be used on waysmay be used on areasshould not be used on relations
Useful combination
Status: approved

A bay is an inlet of a sea or lake which is mostly surrounded by land, but with a level connection to the ocean or lake.

Bays often have calmer waters than the surrounding sea, due to the surrounding land blocking some waves and often reducing winds. Bays can also exist within a lake or pond.

A bay may also be called a sound (or sund), bight, or a bay=fjord (if created by glacial erosion, see fjord on Wikipedia). A cove is a circular or oval coastal inlet with a narrow entrance; some coves may be referred to as bays. For gulfs and very large bays, see place=sea.

How to map

Bays are frequent mapped mapped as nodes, and rarely as areas. Fjords are also mapped as linear ways. When mapping a bay as a node, the node should be placed approximately at the middle of the bay with equal distance to the coast enclosing the bay on all sides. When mapping bays as an area consider the following:

  • Since the edge of a bay towards open water is often not well defined mapping bays with a large opening can be problematic with regards to Verifiability.
  • The edge of a bay towards land should coincide with the coastline. You should never close the coastline at the outer side of a bay as it is part of the ocean (or the lake) it is connected to.
  • When mapping large bays as areas the resulting multipolygon relations will often be extremely large and complex so mapping with nodes is preferable, like for place=ocean and place=sea. Some mappers also prefer to use approximate or simplified polygons instead of the coastline although such mapping is geometrically not verifiable and can be difficult to maintain because of the additional geometries.
  • There is currently no definitive rule if small islands within a bay should be mapped as part of the bay or if they should be excluded of the bay area as inner rings of the corresponding multipolygon relation. However, if you do not use a multipolygon, any renderer which renders water bodies over land polygons will show the islands as submerged.
  • Fjords (bay=fjord), which are long, narrow bays, may be mapped as a linear way.

Rendering in OpenStreetMap Carto


See also