Thirty-four refugees, almost half of them children, have drowned off the Greek coast after their boat sank, the coastguard said.
Four babies, six boys and five girls are among those who died when the wooden vessel carrying them overturned Sunday morning, about three miles east of the small island of Farmakonisi, close to Turkey's coast.
Details of the nationalities and ages of the victims have yet to be released.
Units of the Greek coastguard said 68 people were rescued from the water and another 30 survivors from the same boat were found on Farmakonisi.
On Lesbos, an island which has borne the brunt of Greece's migrant intake, a Reuters photographer saw 10 dinghies arriving within 90 minutes on Sunday.
One inflatable carrying about 70 refugees, including many children, burst about 100 metres from the shore.
Locals pulled infants and toddlers - including a two-month old baby cradled by his father - ashore on rubber rings.
Tens of thousands of mainly Syrian refugees have braved rough seas this year to make the short but precarious journey from Turkey to Greece's eastern islands, mainly in flimsy and overcrowded inflatable dinghies.
Thousands have died, many of them taking the much longer crossing from Libya, in Europe's worst migrant crisis in decades.
Greece has regularly called for more help from authorities in dealing with the influx, and caretaker Prime Minister Vasiliki Thanou urged the bloc on Sunday to agree a more comprehensive policy.
Other countries were wrong to criticise Greece's response to the flow of migrants, Thanou said during a trip to Lesbos.
"We would urge them to consider the responsibility of guarding a 16,000 km long coastline of European borders ... and whether a future Europe of principles can be constructed by building walls," she said.
The vast majority of refugees reaching Greece quickly head north to other countries, with Germany the most favoured destination.
EU states have so far failed to reach agreement over proposals by Commission president Jean-Claude Juncker to accept a mandatory quota system for accepting refugees.