The second largest island of the Dodecanese has many and excellent places to discover, but nearby there are wonderful islands with quite difficult access and it will be an opportunity to visit them in combination with Karpathos.
Saria is located north of Karpathos and to get there you can take an excursion boat from Pigadia or Diafani. The island is uninhabited by humans, but it's a refuge for several species of birds and wild animals. For this reason it has been declared a Natura 2000 protected area. Saria has crystal clear waters which you can enjoy at Palatia and Alimounda beaches. From Palatia begins the gorges of Saria; a good choice for hiking enthusiasts.
Kasos is about 1 hour far from Karpathos and is definitely a unique destination. Only two days are enough to relax and enjoy truly carefree moments. It may not have many attractions and countless idyllic beaches, but it has extremely hospitable residents, great food and one of the most beautiful beaches in the Mediterranean, Marmara located on the islet Armathia.
Halki is an ideal place to relax and enjoy moments of true tranquility. Arriving at the port of Halki you will see the beautiful settlement, where the courtyards of the houses literally lick the sea. In Emporio it is worth seeing the church of Agios Nikolaos and the clock tower. Visit Chorio, the old capital of the island and climb the Medieval knight's castle to enjoy the magnificent view. For swimming, choose Pontamos, a beach with golden sand and crystal clear waters, which is a 10-minute walk from the port. Alternatively, you can choose the most distant beaches (Ftenaya, Giali, Kania) or even the beautiful beaches that can only be reached by boat (Trachia, Areta).
The journey from Pigadia to Halki takes about 2h 40m, while from Diafani 1h 40m and there are 2 to 3 weekly routes.
There are several other places connected to Karpathos by ferry, such as Rhodes, Santorini, Crete (Sitea & Heraklion), Anafi and Milos, but these are quite large islands and most probably not ideal for short-day excursions.