[OSM-dev] Sea polygons

[Nop]

Hi!


I am looking for a set of sea polygons for use with mapnik.

The shapefiles that are usually referred to as sea polygons are actually 
land polygons drawn on a blue background. I cannot use this technique as 
my land needs to be transparent.

Are there sea polygons that actually cover the sea area?
Is there a way to invert the land polygons to sea?
Is there a way to create sea polygons from the coastlines similar to 
however the land polygons are created?

thanks
	Nop