Challenge Accepted

A Facebook comment on my Goals 0.0 post suggested I should tackle memorizing the major bodies of water in the world first.  I figure why not - it's as good a direction as any.  But now what list do I use?  I can find a list of 31, 147, or over 700 (more than half of these are rivers).  147 feels like a solid compromise, but I'm open to suggestions.