The GeoNames web service for mapping a lat/lng to a body of water are great, but I need to do this a *lot* and don't want to go out over the web each time.
For other regions I've been using Shapefiles, but at this point I'd be happy with any kind of polygon data that details the shapes of oceans, seas, and other bodies of water.
Where does GeoNames source this data from? Is it a publicly available source?