The United Nations refugee agency says that more than one million refugees and migrants have reached Europe by sea since the start of 2015.
It said that more than 80% of the 1 million 573 people arrived in Greece, with the majority landing on Lesbos island.
About 844,000 travelled to Greece from nearby Turkey. Most of the others - over 150,000 - crossed the Mediterranean from Libya to Italy.
The migrant crisis is Europe's worst since World War Two.