Cunda Island, also called Alibey Island, (Turkish: Cunda Adası, Alibey Adası; Greek: Μοσχονήσι or Μοσχονήσος), is the largest of the Ayvalık Islands archipelago in Turkey, which was historically called the Εκατόνησα (Hekatonisa) or Μοσχονήσια (Moschonisia) archipelago in Greek. It lies in the Edremit gulf on the Turkey's northwestern coast, off the coast of Ayvalık in Balıkesir Province, Turkey, with an area of 23 square kilometres (9 sq mi). It is located 16 kilometres (10 miles) east of Lesbos, Greece.
Cunda Island has a typical Aegean resort town. There are frequent bus and ferry services to Cunda Island from the town center of Ayvalık. Cunda Island is connected to Lale Island, and thence to the mainland, by a bridge and causeway built in the late 1960s. This is the first and currently the oldest surviving bridge in Turkey that connects lands separated by a strait.
For some months in 1922, the island was the see of a Greek Orthodox metropolitan bishop, while the neoclassical mansion of the last metropolitan, Ambrosios, who was executed by the Turkish army, still survives on the seafront of the island's town center. On September 19, 1922 several hundred of the Greek islanders were killed on Cunda during the Greek genocide, only some children were spared and sent to orphanages. The next year, following the Treaty of Lausanne (1923) and the population exchange between Greece and Turkey, the few remaining islanders were forced to leave for Greece and were replaced by Cretan Turks and Turks from Lesbos. The main landmark of Cunda Island remains the Taksiarchis Church (Turkish: Taksiyarhis Kilisesi). The large, former Greek Orthodox cathedral was abandoned and dilapidated, but has now been restored.