Defendant and claimant (tour organiser) have concluded a contract for a package tour to Iceland. They have also agreed on an optional excursion to Greenland against payment. Later, the claimant has cancelled the optional excursion. Ten days prior to departure the claimant has informed the defendant that the optional excursion is >doubtful< and five days later, that it is cancelled. The defendant has cancelled the entire trip. In the proceed-ings, the defendant failed to prove that the optional excursion (to Greenland) was the es-sential part of the package travel contract.