How to get to Geysir?
Here is a map from Keflavik Airport: en.ja.is/kort/#x=407010&y=391876&z=4&type=aerial&from=keflav%C3%ADkurflugvelli,%20235%20reykjanesb%C3%A6&to=haukadalur%20II
If you are coming from some other place then the airport, just change the place at "from" (place, adress)
You can also drive through Thingvellir the National Park, Lyngdalsheidi, it is about an hour drive to Geysir from Mosfellsbæ.
GPS: 64°18,603´N, 20°18,024´W