There is a Travel Agent in Diafani, Nikos Orfanos.
He will sell you tickets for the ships going to Rhodes, Crete, Piraeus etc; and help you to arrange Olympic Airways flights from Karpathos. He also sells postcards, stamps, OTE Telephone cards, maps and guide books.
Nikos is the owner of an hotel in Diafani and can also arrange to find you a studio or furnished appartment. He is also the owner of one of the small "Kaïki" boats that takes visitors to the nearby beaches and on excursions to the island of Saria.
Nikos Orfanos Travel Agency is also the local place to change foreign currency. In fact if you need anything at all you can ask Niko, he will always do his best to help visitors.