ATHENS — The bodies of 16 people, including at least five children, were recovered from the sea off a Greek island on Saturday after a boat smuggling migrants sank in the eastern Aegean, a spokeswoman for the Greek coast guard said.

The drownings — the first such mass casualty in several months — came almost exactly two years after Turkey and the European Union signed a deal to curb the flow of migrants trying to reach Europe via the Aegean Sea.

Although the influx has been limited drastically since that time, when daily crossings were often in the thousands, hundreds continue to reach Greek islands in smuggling vessels that are often old, flimsy and unseaworthy.

The Greek authorities were alerted to the latest episode shortly after 8 a.m., when three survivors — two women and a man — swam to the island of Agathonissi and said that a boat carrying 21 people had sunk, the coast guard spokeswoman said.