It is 20 nautical miles from West Istanbul Marina
It is second largest island in the archipelago of Istanbul’s nine Princes’ Islands. Heybeliada was known as Khalkitis or Chalki during the Byzantine period.
 

The highest peak of the Heybeliada is Değirmen Tepe (peak) (136 m). Taş Ocağı Tepe (128 m) is located on the eastern end of the Değirmen Tepe. The other mountains of the island are Umit Tepe (85m) on which Heybeliada Priest School is located, and Makarios Tepe (98m), Makarios Monastery, on which located on top of the island. The island hosts four harbours: Bahriye Harbour, Mendirek Harbour, Değirmenburnu Bay and Çam Harbour. Çam Harbour,  called “Port Saint Maria” in old times, is the greatest harbour of the island and is worthy of being shown as a natural wonder. The Terki Dünya Monastery (meaning “Leaving the World Behind Monastery”) was originally built in the woods by Çam Harbour in 1868, but it was rebuilt from wood after an earthquake occured in 1894. Apart from that monastery, the Aya Yorgi Uçurum Monastery (1758) and the Saint Mary Church, a place of pilgrimage built by V. İoannes Palaiologos in 1341, are also situated on the island of Heybeliada. Ayia Eufemiya Ayazma (holy spring of Orthodox Greeks) is seen as a historical site of the island located southeast of the Naval Cadet School.