They come from every hellhole in Africa. Some come from Syrian refugee camps. Many of them make their way overland to Libya, where the human smugglers offer them risky passage in a leaky boat for a high price. The boats are packed so tightly, people can only stand. Those who die on the voyage are thrown overboard. Those who live dream of paradise in Rome or London or Stockholm.
But it is a deadly lottery. More than 3,200 people died trying to cross the Mediterranean last year; more than 1,500 people have already died this year, including the 700 or more who drowned this past weekend. Many didn't have a chance – according to one survivor, hundreds were locked in the hold.
Now everyone is clamouring for something to be done. Moammar Gadhafi used to control the smugglers, but now he's gone, and Libya is lawless. The European Union can't even agree on who will pay for more rescue boats, much less on who should take responsibility for the rescued. Even the idea of more rescue boats is contentious, because more rescue boats encourage more desperate people to set out to sea, believing they'll survive.
Meanwhile, the flood of refugees could turn into a tidal wave. Last year, around 170,000 migrants reached Italy by sea. This year, says Europe's border security agency, Frontex, another 500,000 or more people are already in Libya, waiting for their chance. The only thing that's stopping them is a shortage of leaky boats.
European law says that every refugee is entitled to asylum. But nobody can agree on who's responsible for the asylum seekers, or who should pay for their upkeep. Many countries argue that the primary responsibility belongs to the country where they first land – which usually means Italy or Greece. Italy and Greece say that's unfair. On top of that, the EU countries have no common asylum policy.
But the real problem is that Europe is struggling with millions of illegal migrants already. And as long as war and unrest continue to tear up large parts of Africa and the Middle East, the human tidal wave isn't going to end.
From the outside, it's easy to be sanctimonious. It's easy to preach (as The New York Times did this week) that Europeans should stop being so selfish and start taking in more refugees. But just how unselfish should Europeans be? How much do they owe the suffering masses of Africa and the Middle East?
Italy, a country I know a little bit about, has a population of 60 million, and it's shrinking. Africa has a population of more than 1.1 billion, and it's growing fast. Italy's migrant growth rate is already the second-largest in Europe, after Spain. Last year, it took in 139,000 refugees and asylum seekers, mostly from Syria and Eritrea. Its economy is terrible. Unemployment in the south is already over 20 per cent. Italians already harbour deep, intractable prejudices against each other, never mind outsiders. (Just ask any northerner about Sicilians.)
What is the prospect that Italy, an intensely tribal nation, will be able to successfully assimilate millions of Middle Easterners and Africans with little education and no skills? Ask yourself this question the next time you visit Florence, where illegal migrants hawk their wares in the shadow of the Duomo. The answer is slim to non-existent.
What Europe's political class can't bring itself to admit is that a humanitarian solution to the refugee crisis is not compatible with Europe's interests. Nor is it compatible with the growing protests of many European voters. To them, the tidal wave of suffering looks more like a siege. As one local politician in southern Italy told National Geographic, "We're the first country to finance its own invasion."
The truth is that the world is full of far more victims of wars, violence, bad governments and political repression than we can ever take in. All we can do is accept a lucky few, and try to discourage the rest of them from coming. One step would be to automatically ship back people who arrive illegally, in order to discourage others from coming. That seems cruel. But political leaders who deny reality will eventually be turfed out by voters who feel besieged. And the leaders who come next won't be so benign.