We need to be careful with these labels, for a few reasons. Using a single point to represent an ocean is quite an oversimplification! These points are also arbitrarily placed, so mappers could get into endless edit wars about where to put them. Many mappers will use them as “labelling positions” rather than ensuring the position has some kind of geographic basis.
The Arctic Ocean label is a good example. From the overpass screenshot I assume the node is outwith the range we render. Do we want just the bottom half of the label showing?
Normally oceans and sea labels are “hand placed” by cartographers, since the challenge of automating the label placement is so high. But we can solve the technical challenges here; while doing so lets remember not to end up rendering “labelling nodes” by mistake.
It definitely shows lake names, it’s just limited to specific zoom levels, e.g. here you should see all the names of the Great Lakes: https://www.openstreetmap.org/#map=7%2F45.064%2F-81.758
The source code of the renderer is here: https://github.com/gravitystorm/openstreetmap-carto
And there is an issue about displaying sea and ocean names: https://github.com/gravitystorm/openstreetmap-carto/issues/2278
Rationale from @[email protected] as an issue comment: