This cave is located on the south side of Kastelorizo and you can visit it only by boat. It is also known as Cave of Parastas or Fokiali (because of the seals that live there). It is considered one of the largest and most beautiful sea caves in Greece and is known internationally for its rich stalactite decoration. It was created during the Pleistocene period due to the karstic erosion of the limestones.
The cave is 155 m. long. The highest part of the cave is 25 m. and is covered by colorful stalactites. They are usually illuminated by the reflections of the sun creating a spectacular scenery. The second chamber of the cave is the shelter of the Monachus Monachus seal. The entrance of the Blue Cave is so small that barely fits a small boat in height when the waters are calm.