Diavata Refugee Camp, Greece (CNN) Imagine watching as violence and bloodshed took over your country, leaving you with little option but to flee.

Imagine risking your life, traveling hundreds of miles, and throwing yourself on the mercy of strangers in a foreign land.

Now imagine doing all that as a child, with no parents, no family to support you on the perilous journey.

Dozens of teenagers in Greece's Diavata refugee camp don't need to use their imagination -- this is the life they've been living for weeks, months, even years.

Ashraf Khalil Alhatem, 17, and his 15-year-old brother Hatem left their home in Deir Ezzor, Syria, at the urging of their parents, who stayed behind with the rest of the family.

"They were worried about the military bombing everything, and we weren't able to continue our studies or live with any kind of safety," he explains.

Ashraf says it took the pair two attempts just to cross into Turkey: "The Turkish army blocked us so we returned, but we tried again and thank God we got through."

Perilous journey by sea

After more than three weeks in Turkey, the brothers got onto a boat heading for Greece — but their journey was far from straightforward.

"In the sea we stayed in the Straits of Turkey for three days, without food or any water at all," says Ashraf.

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"My brother has a problem with his heart so we were always worried about him. I didn't know what to do — it was a very difficult situation."

And things didn't get any easier when they finally landed on Greek shores.

"I was jailed twice," says Ashraf. "And now we are living in tents. Really awful tents. My mood is very tired, and the situation is very difficult. But hopefully things will get better, God willing."

Ashraf and Hatem are two of the 30 or so unaccompanied minors -- all of them boys -- living in Diavata; girls are housed in a government-run shelter.

Sleeping on benches

In 2015, the European Union registered more than 88,000 child and teenage refugees traveling alone.

Obada Khdier, 17, from Damascus, dreamed of studying to become a doctor, until the Syrian civil war interrupted his studies. He says he fled his home because "there was no way to live normally or in safety" in Syria.

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After arriving in Turkey, he went hungry and slept on park benches for a week before a passerby offered him a place to stay and helped him find a job.

"In Turkey the life I had only allowed me to live and eat and drink, it didn't provide me with any sort of a future," he says, and after eight months he decided to move on "so I could have a future and carry on with my studies."

Like many others, the Khalil Alhatem brothers and Obada crossed into Greece by sea. Last year at least 856,000 people risked their lives to cross the Aegean on rickety boats and inflatable dinghies.

Thrown in jail

But once Obada arrived in Greece he found that his age, and the fact he had nobody with him, meant his way on was blocked.

"I couldn't continue my travels because I was a minor — I needed to find a family that would sponsor me."

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Obada found a family to travel with, but four days after arriving at a refugee camp, they left him behind.

"I stayed in the camp for a month and half by myself, and [then] I went to the police and said, 'I am a minor and I am by myself here.'

"The police arrested me and I stayed in jail for 15 days — the reasoning being that I am now the responsibility of the country because I am a minor."

Eventually, Obada was helped by a social worker from Arsis, an NGO which helps unaccompanied minor refugees.

He now plans to travel on to Germany where, he says, "hopefully I will be able to realize my potential and fulfill my dreams."

Borders closed

Harth Mohammed, 16, ran away from his home in Mosul, Iraq, to escape ISIS. "I was looking to continue my studies and most importantly be somewhere safe away from war," he says. "All I want to do is be in a safe place and have peace of mind."

Ali Misbah Noori, 14, traveled to Europe from the Afghan capital, Kabul. He says he had no choice but to come alone because "my father had enough money to only send me."

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"I started my journey first to Pakistan and then from there to Iran and then to Turkey and finally I arrived in Greece — my journey in total was around 70 days.

"I am not comfortable here," he says. "I was planning to go to France, but as the borders got closed, now I am stuck in here."

In March this year, the European Union sealed the border between Greece and the Balkan states, and made a controversial deal with Turkey to take back refugees, saying the region is simply overwhelmed.

That agreement has left some 57,000 people stranded in tented camps across Greece, according to the U.N. — they can't move forward into Europe, and refuse to return to Turkey, which is already home to close to three million refugees.

Life in limbo

Sisters Riam, nine, Lina, six, and Dima Suleiyman, five, also got stuck in Greece when the border was closed, though they, at least, have their parents with them.

"When we arrived to the border it was our turn to go through and then the border closed," says Ahmed (not his real name — the couple asked CNN not to reveal their identity, fearing relatives back home may be targeted).

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"In our face," adds Zinah (not her real name). "People before us can enter, but we cannot. I was standing before the border and they said the border is closed and now you have to back. It is very sad."

Two years after fleeing their home in Homs, the family is now living in limbo in the Lagkadiki Refugee Camp.

With little to do and "no [real] school for the children here," Ahmed says he and Zinah are trying to teach the girls themselves, to fill the days: "We teach them Arabic and some English, and sometimes we draw some drawings."

Ahmed says he is trying to learn Greek, but that he knows it will be tough to find work in the country.

"I speak English, I speak French and I am an electronic engineer, so I can help any community, any society -- I can integrate with them, [but] I know the Greeks here have economic crisis, so how can I have work for me when I am not Greek guy?"

Skype calls for asylum

The family is eager to move on: "This is no life," says Ahmed. "Without work, we spend our time sleeping and eating, sleeping and eating, it is boring."

But, Ahmed says, anything is better than life at home in Syria: "Sometimes when we are depressed, we wish we were staying in Turkey maybe. But we can't stay in Syria, because almost every second you may die."

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To move on, though, both families and unaccompanied minors have to apply for asylum in Europe. To do this, each has to make a Skype call to the Greek authorities. The line is open for just an hour a day, and thousands are trying to get through at the same time.

The Halle family from Aleppo has been calling for more than 60 days in a row — and they still haven't managed to speak to anyone.

"I've been calling for two months and seven days," explains father-of-two Anas Halle, who came to Greece with his wife, sons and other relatives. "It's tough. I just dialed again. But ... there is only that noise."

In the hour the line is open, they call the number over and over — 36 times today — with no luck.

Daydreams of the future

"Of course, it's a ploy," says Anas's wife Maryam, as their young son Lais whines in boredom beside her. "Is it even possible that they could answer the phone calls of so many thousands of people?"

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The Greek government says an in-person registration service will soon be set up in camps. Until then Skype -- and daydreams of the future -- are the only option.

"It's not good here," says Lais, aged six. "I would like some toys. And some chocolate. Do you want to know where I want to go?" he asks. "Germany."

Ashraf Khalil Alhatem says he and his brother don't mind where they end up — as long as they are away from the war in their homeland.

"I want the ability to continue my studies and have safety for me ... and to protect my brother and for him to continue his studies and for me to give him medicine. He has a problem in his heart and needs an operation.

"It doesn't matter where I go — the most important thing is that its safe."