Greece’s caretaker prime minister, Ioannis Sarmas, declared three days of national mourning on Wednesday. President Katerina Sakellaropoulou, who holds a largely ceremonial office, visited the port of Kalamata, in southwestern Greece, where some people were protesting the government’s tough stance on migration.

How deadly are these migrant routes?

The sinking was the deadliest such episode off the Greek coast since 70 people died when a boat carrying migrants sank near the island off Lesbos in October 2015, according to the International Organization for Migration.

Last year, nearly 3,800 migrants died on routes within and from the Middle East and North Africa region, according to a new annual report by the organization — the highest death toll in five years, the report said. And given the scarcity of official data, the actual number of deaths on those routes is probably much higher, it said.

“As many as 84 percent of those who perished along sea routes remain unidentified, leaving desperate families in search of answers,” the report said.