* Hundreds attempt crossing from Turkey each night

* Eastern Mediterranean route has become main gateway

* Turkey struggling to cope with humanitarian crisis

By Ayla Jean Yackley

IZMIR, Turkey, Aug 19 (Reuters) - They dress in shorts to blend in with the tourists, buy cheap life jackets and balloons to protect themselves and their belongings at sea and play cat and mouse with police over places to sleep.

They are among tens of thousands of Syrians who have descended on the Aegean port city of Izmir this summer before catching a boat to Greece, their gateway to the European Union.

Iraqis, Iranians, Afghans and others also pass through, part of the biggest global movement of refugees ever recorded.

Paying traffickers to smuggle him by sea in the dead of night is a "deal with the devil" that Alaaeddin, a Syrian who fled Aleppo after four years of war, says he has no choice but to make.

"I am afraid of the smugglers, men who take money from desperate people," the 29-year old says, asking that his surname not be used because he fears for his safety. "But it is impossible for me to go back, and if I stay here, I fear I will be lost. I have to keep moving if I am to have a life."

The crisis has dragged the wars of the Middle East to Europe's doorstep, crippling depression-hit Greece and sapping Turkish resources as it cares for 1.9 million Syrians and 200,000 Iraqis.

Turkey has won international praise for its open-door policy on Syrians, making it the world's leading host of refugees. But European Union Affairs Minister Volkan Bozkir warned in July that it was at capacity and that any new wave would end up pressing on Europe's borders.

On any given day, as many as 5,000 migrants throng Izmir's streets waiting for passage to Greece, aid groups say. By night, buses and trucks run them to remote coves, and at first light, they crowd into inflatable motor boats or rickety dinghies that ferry them to Greek islands less than 10 miles (16 km) away.

Worried about piracy, they carry little cash and seal passports and phones in balloons in the event boats capsize.

"We are face-to-face with a humanitarian crisis on our streets that we cannot cope with. We're unable to meet so many people's needs for housing, food, water, hygiene and health," says district mayor Sema Pekdas, adding those leaving for Europe are a small proportion of the 200,000 Syrians in Izmir.

Outside her office, families crowd the street, waiting to board buses to the shore.



FORCED INTO BACKSTREETS

Strife and persecution around the world displaced 59.5 million people -- half of them children -- last year, the greatest number ever recorded, the U.N. refugee agency UNHCR says. Millions more are fleeing poverty and instability for a better life in affluent but increasingly hostile Europe.

The so-called eastern Mediterranean route from Turkey has become the main gateway to Europe, according to Frontex, the EU border-management agency. A record 49,550 migrants reached the EU via Greece in July -- more than in all of 2014, it says.

Hundreds of islands ensure calm waters in the azure Aegean Sea, offering safer passage than north Africa to Italy, where most of the more than 2,000 migrants who have drowned so far in 2015 perished.

But the Aegean can be treacherous. A boat overloaded with 31 Syrians sank on Tuesday, and six, including an infant, drowned.

Kos and Lesbos, normally tranquil Greek resorts, have been overwhelmed in recent weeks by migrants and refugees, who have at times clashed with one another and police.

The atmosphere is less bleak in Izmir's rundown Basmane neighbourhood, where a half-millennium ago during the Ottoman era, Jews fleeing the Spanish Inquisition also found safety.

Once-grand 19th Century villas have been converted into cheap hotels. Dozens of men dressed in shorts and T-shirts line up at a restaurant serving Syrian cuisine for a last meal before leaving. Many express joy at being so close to Europe.

In recent days, authorities have cleared city parks, forcing migrants into Izmir's backstreets and mosque courtyards. Babies sleep in cardboard boxes to shelter from the blistering heat.



'ONLY OPTION'

Alaaeddin, who studied economics and had hoped to enter politics, opted against a $40 per-night room at a boarding house, spending nights on the street. His white shirt and jeans are grimy, but he carries an electric razor to stay clean-shaven and nibbles on flatbread and bums cigarettes to ease his hunger.

He arrived in Istanbul in May, hoping to join his girlfriend in Egypt, but was denied a visa. Unable to afford tuition costs in Turkey, "Europe became the only option," he says.

He found a trafficker on Facebook, who summoned him to Izmir, where he entrusted the $1,100 payment, his bag and remaining cash to a consignee who, for a fee, will pay the smuggler and forward Alaaeddin's possessions once he sends word.

A strong swimmer, he decided to forgo one of the knockoff life vests sold at Basmane shops for 50 lira ($18), their material making them look more of a liability than a lifesaver.

Turkey is obliged by treaties to stop the flow and has boosted security at borders. But it struggles to integrate refugees and views their stays as temporary, said Metin Corabatir, a former UNHCR official who heads the Research Centre on Asylum and Migration. "If you can't give them reasons to stay, you can never prevent them from leaving," he said.

Every night an estimated 500 people set off, and coast guard officers say they are overwhelmed. The coast guard has rescued 36,000 people this year, including 330 one morning this month.

The group, which included newborns, sat for hours at a marina with little water and no shade as coastguard officials recorded names and surprised holidaymakers watched from their yachts.

For Jassim, 19, it marked the second failed attempt to reach Greece. He fled the Islamic State-controlled town of Membej near Aleppo the week before after witnessing a beheading and learning jihadists had cut off his neighbour's fingers for smoking.

"Either I die in Syria or I die in the sea," he says, tugging on a cigarette. "I would rather die at sea."

(Editing by Nick Tattersall and Philippa Fletcher) ((ayla.yackley@thomsonreuters.com; +90 212 350 7000; Reuters Messaging: ayla.yackley.thomsonreuters.com@reuters.net))