How to identify the sea/ocean as a relationship to coastlines or POIs

Currently I am investigating how to best identify bodies of water that are near by to a user of our app. The focus is for visually impaired users. Whilst enclosed bodies of water such as lakes look straightforward to identify, and rivers, canals and streams also look straightforward, unenclosed bodies of water such as the sea or the ocean seem less so.

For example, the Atlantic and Pacific oceans seem to be defined as a POINT.

e.g. Pacific Ocean: https://www.openstreetmap.org/node/305640005#map=5/-0.967/-120.916

If I select a location on the Pacific coastline e.g. https://www.openstreetmap.org/edit#map=16/36.4356/-121.9214

I can see that this coastline has a relationship with a State Park, but not with the sea. I was hoping that there would be some relationship with the sea, and that the sea had a name. Therefore, our app could call out “Coastline with Pacific Ocean” for example.

Similarly, a causeway on the island of Jersey is surrounded by water on both sides but there is no OSM relationship with the sea that I can see.

Is there another way of identifying the sea?

Thanks
Steven

I think you will need to hard code rules for determining which ocean a body of water belongs to.

Do ocean’s actually have legally defined boundaries anyway, or just blend into each other in a fairly informal way?

@hadw I think you may be right.