The Greek coast guard said a wooden boat with about 50 people on board sank after it left Turkey early in the morning.
Thirteen people are still missing, but 26 were rescued.
The deaths are just the latest in what has turned out to be a dangerous passage between Turkey and the Greek islands in the Aegean Sea this year.
The International Organization for Migration (IOM) says more than 900,000 migrants made sea crossings into Europe this year from countries in the Middle East and Africa. Thousands more are trying to make the trip.
The IOM reports almost 5,000 migrants were rescued in the first part of December by the Italian coast guard and Navy.
The organization says over 21,000 migrants arrived in Greece by sea this month.
In total, 3,600 migrants died making journeys from their home countries to Europe this year.
On Tuesday, the Associated Press news agency reported six children died after a rubber boat sank shortly after leaving Turkey.
Words in This Story
migrant - n. someone who moves from one place to another, usually for economic reasons
passage – n. a voyage or journey usually on a boat
journey - n. a trip