Biking the Danube--Passau to Vienna--in May. If you are a biker, this is a fabulous, not-very-difficult 5 day bike ride. Go in May when the apricot and apple blossoms are at their peak and the heurigers beckon. No need for elaborate plans, small inns are easy to book into on the spot. Here is a picture from the end of a beautiful day as we rode into Durnstein.