The controversial deal sees failed asylum seekers expelled from Greece
The first migrants have been returned to Turkey as part of a European Union deal to deport those who have failed to gain asylum.
Ships carrying around 200 migrants and refugees left from the islands of Lesbos and Chios this morning.
Some human rights groups are concerned about the legality of the deal and how it is being implemented.
Johan Eldebo is a senior humanitarian adviser at World Vision.
The first boat with several dozen passengers on board arrived at Dikili on the Turkish coast at around 9.20am (local time), accompanied by two Turkish coastguard vessels and a police helicopter.
They were taken to a small white tent on the quayside, behind security fencing, where they were met by immigration officials as they disembarked.
"All of the migrants returned are from Pakistan except for two migrants from Syria who returned voluntarily," Giorgos Kyritsis, a spokesman for a government refugee crisis committee, told state television.
He said there was "no timetable" for further deportations, adding the examination of asylum applications "will take some time".
Human rights groups argue the collective deportations break international law and mark a dark time in Europe's history.
Lucy Carrigan, from the International Rescue Committee, said: "What is missing is the focus on what the legal alternatives are - how can desperate people seeking sanctuary, who are fleeing war, find a way to Europe safely".
As each migrant was led aboard a ship, a small group of protesters outside the port in Lesbos shouted "shame on you!".
Riot police officers also boarded the boats.
Turkish Interior Minister Efkan Ala said they had made provision to receive 500 people on the first day, but the Greeks had only provided the names of 400.
For each migrant sent back to Turkey, a legitimate refugee will be resettled in Europe.
As the deportation process got under way, the first group of 16 Syrian asylum seekers arrived in Hanover, Germany on a flight from Istanbul.
Although the first migrants to be sent back are expected to be from Pakistan, Afghanistan, Iraq and Iran, Syrians who have illegally crossed will also be expelled under the deal if they have arrived since March 20th.
Earlier, Helena Smith of The Guardian told Newstalk Breakfast the first deportees were sent off earlier than expected this morning.