Great work! It might be cool if you could use voronoi diagrams to select the closest path to the mouse's position like the NYT did [0] because without really zooming in, the lines on some terrains appear to be very thin which makes hovering over a specific one a little harder.

There's also a great talk that discusses this from JSconf2014 [1]

[0] http://www.nytimes.com/interactive/2012/11/02/us/politics/pa... [1] https://www.youtube.com/watch?v=90NsjKvz9Ns