For clarity, Iceland, Norway, and Switzerland, ( plus Liechtenstein ), are WITHIN the Schengen zone, as shown here :
http://www.schengenvisainfo.com/schengen-visa-countries-list/
This is through the introduction of the treaty of Amsterdam, which affects EEA/EFTA members as well as EU states ;
"....Notes that there is a direct effect in areas such as the Common Foreign and Security
Policy. visa, asylum and immigration policy and the removal of border controls
(Schengen)."
http://www.efta.int/sites/default/files/documents/advisory-bodies/parliamentary-committee/jpc-resolutions/May-1998AmsterdamTreaty.pdf