Avşa Island (Turkish: Avşa Adası) or Türkeli is a Turkish island in the southern Sea of Marmara with an area of about 20.6 square kilometres (8 square miles).
The Greek inhabitants fled to Sarti Chalkidiki after the 1923 population exchange.
The island belongs to the Marmara District of Balıkesir Province in northwestern Turkey.
The local population is around 2,000 according to the last census, but during the summer season the number of visitors increases as far as forty to fifty thousand.
The exact location of Avşa island is shown in the following map in red color.