Nowadays Guam is incorporated territory of US in the western Pacific Ocean, check the visa requirements prior your departure to this destination. Promotional tariff of KLM allows to purchase such a flights in travel period till 30th of June 2015. Max stay 1 month. This KLM promotion is valid for bookings made till 29th of April 2015.
Booking samples
DE - Germany - Guam from €715
EN - Germany - Guam from £526
NL - Dusseldorf - Guam from €733
Travel dates are the easiest to check here http://flynous.digidip.net/visit?url=http%3A%2F%2Fwww.ebookers.de%2Fshop%2Fairsearch%3Ftype%3Dair%26ar.type%3DroundTrip%26strm%3Dtrue%26ar.rt.leaveSlice.orig.key%3DD%25C3%25BCsseldorf%252C%2BDeutschland%2B-%2BAlle%2BFlugh%25C3%25A4fen%2B%2528DUS%2529%26_ar.rt.leaveSlice.railAndFlySelected%3D0%26ar.rt.leaveSlice.dest.key%3DGUM%26ar.rt.leaveSlice.date%3D14.05.15%26ar.rt.leaveSlice.time%3DAnytime%26ar.rt.returnSlice.date%3D28.05.15%26ar.rt.returnSlice.time%3DAnytime%26ar.rt.flexAirSearch%3Dtrue%26_ar.rt.flexAirSearch%3D0%26ar.rt.numAdult%3D1%26ar.rt.numChild%3D0%26ar.rt.child%255B0%255D%3D%26ar.rt.child%255B1%255D%3D%26ar.rt.child%255B2%255D%3D%26ar.rt.child%255B3%255D%3D%26ar.rt.child%255B4%255D%3D%26ar.rt.child%255B5%255D%3D%26ar.rt.child%255B6%255D%3D%26ar.rt.child%255B7%255D%3D%26_ar.rt.nonStop%3D0%26_ar.rt.narrowSel%3D0%26ar.rt.narrow%3Dairlines%26ar.rt.carriers%255B0%255D%3DAZ%26ar.rt.carriers%255B1%255D%3DDL%26ar.rt.carriers%255B2%255D%3DAF%26ar.rt.cabin%3DC%26search%3DSuchen&ppref=http%3A%2F%2Fwww.flynous.com%2Fwp-admin%2Fpost.php%3Fpost%3D911%26action%3Dedit%26message%3D1using +-3 days searching tool as it vary depends on chosen airport of departure.
If interested in this KLM promotional offer please refer to above booking samples. You may also decide to book stop-over in Taipei for additional cost. In some cases you would have to accept longer layover in Japan giving you an option to experience another culture and explore another city during your trip.
Booking sample of cheap flights to exotic Marianna Islands. Air tickets from Germany for €715 here. In this case you would be departing from Hamburg to Guam on 16th of May. Your return flight from Marianna Islands back to Germany would take place on 26th of May 2015.