Eleven people were killed and about 40 are missing after a boat carrying migrants from Turkey to the Greek island of Lesbos capsized, Greek state media reported on Thursday.
Eleven bodies recovered by the coast guard and fishermen included those of two children, state radio ERT reported, saying that 242 people had been rescued in an overnight operation.
Many of those rescued, including dozens of women and children, were taken to hospital suffering from hypothermia.
The Greek coast guard said it had rescued 900 migrants in the Aegean Sea over the last 24 hours.
Lesbos is a main gateway to Europe for people escaping conflicts in the Middle East who cram into tiny boats in Turkey for the short – but dangerous – sea journey to the Greek island.
The journey is more dangerous in winter, when the sea is rough.
Some 368 people died this year trying to reach Greece from Turkey by sea, according to the International Organization for Migration.