"I extend my greetings and wish you success at the Olympic Games in Rio -- that your courage and strength find expression through the Olympic Games and serve as a cry for peace and solidarity," wrote the Pope.
"Your experience serves as testimony and benefits us all. I pray for you and ask that you, please, do the same for me."
Soon after details of the Pope's letter were published, the 18-year-old Mardini jumped in the Olympic pool and won her heat in the 100 meter butterfly -- though she didn't swim fast enough to progress any further.
Aged 14, Mardini swam for Syria at swimming's short-course world championships in 2012. But with her home destroyed in the ongoing conflict, she and her sister decided to flee the country in August last year.
From Lebanon they reached Turkey and then took a boat to Greece -- but the boat began to slowly sink as it took on water during the journey.
Mardini had to jump into the water and, summoning all of her swimming and survival know-how, help push the boat and its occupants until it safely reached Greek shores.
"I thought it would be a real shame if I drowned in the sea, because I am a swimmer," is how she summed up the nightmare to reporters earlier this year. She is now living and training in Germany.
Leaving everything behind
"These refugees have no home, no team, no flag, no national anthem," International Olympic Committee president Thomas Bach said when he announced the selected athletes last month.
The IOC came up with the plan in March, creating a $2 million training fund and shortlisting dozens of refugee athletes for potential selection.
"We will offer them a home in the Olympic Village together with all the athletes of the world," Bach said.
The final team for Rio includes 10 athletes competing in three sports. Half are refugees from South Sudan, two fled Syria, two left the Democratic Republic of the Congo and one is originally from Ethiopia.
Bach added: "These refugee athletes will show the world that despite the unimaginable tragedies that they have faced, anyone can contribute to society through their talent, skills and strength of the human spirit."
From Kakuma to Rio
Five of the 10 athletes grew up in Kenya's vast Kakuma refugee camp before joining a special track and field project.
Tegla Loroupe used to be one of Kenya's top marathon runners. The 43-year-old now runs a foundation in her name, partly dedicated to helping refugee athletes train. She will be the refugee team's leader in Rio.
Last year, Loroupe's foundation came to the Kakuma camp and began to hold tryouts for residents.
The camp, in Kenya's northwestern corner near the border with Uganda and South Sudan, holds more than 180,000 people -- roughly the size of Swindon in the UK or Salt Lake City in Utah.
Returning from a trip to Kakuma in January, top International Olympic Committee official Pere Miro said sport appeared to be one of few things keeping refugees going in such a harsh environment. Kakuma has more than 100 football teams, for example, and dozens of basketball teams.
Now, it has five Olympians too.
Yiech Pur Biel had been at the camp for a decade when Tegla Loroupe's foundation showed up to hold trials. The 21-year-old, a refugee from South Sudan, was a good enough runner to be chosen for Loroupe's training center -- despite having no shoes at the camp -- and will now race in the 800 meters for the refugee team in Rio.
Joining him is James Chiengjiek, who fled South Sudan to avoid becoming a child soldier in a decades-long civil war that claimed millions of lives. He arrived at Kakuma in 2002.
Now in his late 20s, he had been one of Loroupe's athletes since 2013 and will run the 400m in Rio. Paulo Lokoro, who left South Sudan to join his mother at Kakuma in 2004, runs the 1,500m.
Loroupe's foundation is sending two female South Sudanese refugees to Rio. Anjelina Nadai Lohalith, 21, is one of them: She came to Kakuma at the age of six and began running at one of the refugee camp's schools.
In an interview with Rio 2016 organizers earlier this year, Lohalith described her surprise at being chosen to train for the Olympics.
"During the selection it was just like a trial," she said, "but suddenly they say: 'You will be going for training here.'"
Lohalith, entered in the women's 1,500m, will be joined by 800m runner Rose Lokonyen on the team. Lokonyen, 23, was a resident at Kakuma from 2002 until joining Loroupe's team in 2015, despite her parents returning to South Sudan in 2008.
Strangely, the place these refugees called their new home for many years may soon be wiped off the map itself. Kenya says it will soon close Kakuma due to national security concerns, although it has not specified a date and it's not clear what will happen to the residents.
For now, there will be time to gather and follow the fortunes of their five former neighbors in August.
'It would be a shame if I drowned'
Like Mardini, Rami Anis is another accomplished swimmer.
The 25-year-old Anis had been expected to make Syria's team for London 2012 in the men's 100m butterfly event. But in 2011, faced with bombing in his hometown of Aleppo and the prospect of an army call-up, he decided to follow his brother to Turkey.
However, four years later, Anis remained barred from competing with his teammates as he was a refugee. With help from smugglers he chanced a terrifying dinghy trip to Greece then made his way to Belgium, where he was finally granted asylum in December last year.
"This is a dream for any athlete," Anis told a press conference ahead of the 2016 Games. "When I was a child I would dream about participating in the Olympics and our dream about participating in the Olympics under my country's flag.
"However, I am proud that I am participating today even though I am participating as a refugee Olympic athlete. Obviously, I think about my homeland, Syria, and I do hope that by Tokyo 2020 there will be no refugees, nothing is nearer and dearer to my heart than the homeland."
Now he trains at the Royal Ghent Swimming Club under former Belgian star Carine Verbauwen. When Anis was selected, Verbauwen said: "If he stayed in Syria -- if there was no war -- he would have been in the Olympic Games. I think this is justice."
Anis, meanwhile, has tried to keep a low profile in the buildup to his Olympic debut. He has complained, Verbauwen said, that after months of trying to forget what has happened to him, he is now being asked to relive his journey time and again. His motto is simple: now, "the swimming pool is my home."
Yonas Kinde, at the age of 36, is by some distance the oldest member of the Olympic Refugee Team. Kinde lived in Ethiopia until, he says, political and economic difficulties made it "impossible" to continue in his country as an athlete.
Kinde left Ethiopia in 2012 and reached Luxembourg, where he has since been earning a living as a taxi driver while continuing to train as a distance runner. He will be on the Rio men's marathon start line.
"This chance is special for me," said Kinde on being chosen for the team in June. "I've won many races but I don't have a nationality to participate."
Breaking free in Brazil
The final two members of the refugee team won't have to travel far for their first Olympic appearances.
Yolande Mabika and Popole Misenga were members of the Congolese judo team at the 2013 world championships -- in Rio -- when they decided to escape.
Misenga, 24, had seen his mother murdered when he was six years old before fleeing into the rainforest to avoid fighting in his hometown of Kisangani. Rescued a week later, he went on to learn judo at a home in the capital, Kinshasa -- which is exactly how 28-year-old Mabika had taken up the sport when she, too, was evacuated to the same city.
But life on the DR Congo judo team offered little respite from hardships at home. Both athletes say their coaches would assault them and hold them in cage-like cells if they lost. Sometimes, there would be no food.
As the 2013 world championships closed, Mabika and Misenga made a break for a northern Rio neighborhood and sought political asylum. They have remained ever since and are likely to be warmly received by their adopted home crowd when the Games begin.
"Their previous treatment seemed to be subhuman," the duo's new coach, Geraldo Bernardes, told the Guardian newspaper this year. "Here, everyone supports them."
Misenga is now married to a Brazilian and has a one-year-old son. He will compete in the men's 90 kg category with Mabika in the women's 70 kg event.
"I want to win a medal and inspire refugees from all over the world," Misenga told Rio's organizers as he prepared for the Games.
"Afterwards, I want to stay in Rio. God has made this a magical place."
Beyond the refugee team
The official Olympic Refugee Team won't be the only place you can find refugees competing at the Rio Games.
Iran-born taekwondo fighter Raheleh Asemani, for example, was shortlisted for selection to the refugee team but has since been awarded citizenship and picked for Rio by her new home country of Belgium. She already has a European bronze medal with her new team.
Another example is Tsegai Tewelde, who will run in the men's marathon for Team GB. The 26-year-old sought political asylum in Britain eight years ago, having grown up in Eritrea. At the age of eight, Tewelde was injured in a land-mine explosion that killed a friend -- and he still bears a scar from the incident on his forehead.
Nor is this the first time a form of refugee team has been planned, although it's the first time the IOC has agreed to it.
Back in the early 1950s, a group called the Union of Free Eastern European Sportsmen -- started in Hungary and secretly backed by the United States -- tried to set up a team of exiled eastern European athletes for the Olympics as the Cold War intensified.
The IOC rejected that bid. On hearing that the athletes' application had been denied, Hungarian official Anthony Szapary -- who backed the plan -- said in a letter to the New York Times: "For 'choosing freedom' they are now banned from the greatest sports event of the world."
In Rio, that will no longer be the case.