|natural = bay|
|Named area of water mostly surrounded by land but with level connection to the ocean or a lake.|
|Rendering in openstreetmap-carto|
|Used on these elements|
|Status: de facto|
|Tools for this tag|
This tag is for marking named bays. Note that this tag is not for tagging presence of water, this is done using natural=water, natural=coastline (and also waterway=riverbank, landuse=reservoir). Parts of area with natural=bay area may be land - for example islands may be considered as being a part of bay and mapped this way.
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). 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 frequently 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.
- Large bays can be mapped as areas but 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 from 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.
Since bays are generally part of a larger waterbody and may include also land (for example islands), either a lake or the ocean, they should not be rendered in solid color indicating water themselves. The Standard tile layer renders named bays with a label.
Rendering in OpenStreetMap Carto
- natural=bay + bay=fjord