I have several thousand locations in a database, Location A travelling to Location B, New York to London, Paris to Buenos Aires.
I'm trying to plot a path between two places only over sea. I'm not looking for strict shipping lanes or that the start and end points are in a port, if the start/end point is close to New York then that's good enough.
I've been looking for an API service to do this work, Google maps provides a path between two locations but you can't restrict the path to ocean only.
Are there any services where you can plot a very simple polyline between two locations over sea programatically?