Interactive maps can both be functional and, when combined with data, tell a good story. Kiln released this data-driven map (make sure to hit the play button) to show the routes of every cargo ship moving about on the high seas in 2012.
Created by London-based data visualisation studio Kiln and the UCL Energy Institute
How something like this is created can be mind-boggling. Kiln has a service called Flourish that helps with the lifting and we recently shared Observable, which has a similar aim. Sarah wrote up an entire tutorial on creating serverless data visualizations.