A pair of hands appeared to be waving at her from the deep-blue waters of the Aegean Sea.
Maybe it was a diver; maybe it was someone else. Tsiligeridu's husband Dimitris eased up on the controls of their twin engine motor boat and veered left in order to avoid him.
But as they got closer, Tsiligeridu realized something terrible was happening, and she screamed at Dimitris to turn around.
What she saw next would stay with her forever.
There, bobbing up and down in the choppy waters, was a half-conscious man clinging desperately to a lifejacket.
"The waves were massive," Tsiligeridu, a former model and actress, told CNN. "When we got close, we saw a person in a horrible state."
Tsiligeridu says she suppressed her fear of big waves and let her reflexes kick in. Leaning over the edge of the boat, she grabbed the man's hand, and her friends helped pull him out of the sea and onto the deck.
"He was so weak that he couldn't even stand or walk," she recalls. "The only thing he managed to say was that he was from Syria."
'They threw him a lifejacket and then he was lost'
Tsiligeridu says they immediately called the Greek Coast Guard, who told them the man's story.
On the same day as these happy-go-lucky Greek holidaymakers were planning a snorkeling excursion to the island of Pserimos, Mohammed Besmar was preparing for a much more harrowing journey.
At the break of dawn, Besmar stepped off of a beach in Turkey and into a small boat bound for Kos with 39 other refugees fleeing Syria's civil war.
But they soon ran into trouble: the boat lost one of its oars, and Besmar selflessly jumped into the sea to retrieve it, putting his life at risk to save the other passengers, some of whom were ill.
"Mohammed was the bravest of them all and he jumped into the water to grab (the oar) so they can make it to Greece," Tsiligeridu told CNN.
"But because of the strong currents and the big waves he was not able to get back to the boat -- the rest of the people only managed to throw him a lifejacket and then they completely lost him."
Besmar floated away, lost at sea for 13 hours with only a lifejacket keeping him from certain death, Tsiligeridu says.
"Boats were passing him by and he didn't have the power to shout. He didn't know if they could see him or not, he didn't know anything and had lost his orientation," she says.
A Coast Guard official in Kos confirmed the overall story and said they had launched a search mission to find Besmar, but declined to give specific details surrounding his disappearance to CNN.
The official, who spoke on the condition of anonymity, said the Coast Guard was told Besmar was missing at sea when the refugees aboard his boat reached shore.
'Saving him was the most natural thing in the world'
By the time Tsiligeridu and her friends plucked Besmar out of the sea, he was half-conscious, she says.
"He was shaking and he had hypothermia," she told CNN. "Thank god my husband is a doctor, he gave him first aid."
"I immediately grabbed our towels and covered him. I hugged him and was trying to keep him as warm as possible."
Then Tsiligeridu, overcome by it all, broke down.
"I was sobbing (the whole time), because from the moment I saw the person in the water my soul became so deeply saddened that it felt like I was in his position," she says.
"I didn't think at any point if what we're doing was dangerous, if it was allowed or illegal -- a human soul was in danger and trying to save this person was for me the most natural thing in the world."
Soaking wet and exhausted, Besmar was brought to shore, where they parted ways for the time being.
The following day, Tsiligeridu posted a photo on Facebook of her with Besmar that went viral. To her, the image is poignant evidence of an "act of love."
"It was unbelievable, I cannot explain it," she says. "Without any doubt, my life has changed after this incident because we realized a few things; before, in Greece, we were very angry and frustrated about the situation -- there is no organization, there is no state, no social provision that can help all these people."
"These are innocent human souls, they've done nothing wrong, they're just trying to save their families, their own selves and their children from drowning. It's tragic what's happening."
'I would've been dead in 10 minutes'
On Facebook, Besmar thanked Tsiligeridu and offered a heartbreaking explanation for his decision to risk his life to reach Greece.
"Before I thank everyone who contributed to save [my] life from death by drowning, I want to apologize [to] the Greek government, because I entered the ground illegally, but I did not find any other solution to escape from the hell of war in my country Syria," he wrote.
Tsiligeridu told CNN she has spoken to Besmar since then. She says he told her that he would have been dead if she'd arrived 10 or 15 minutes later. He's recovered since then, she says, and they're planning to meet in Athens this week.
Besmar's rescue is a much-needed piece of good news amidst the relentless torrent of tragic stories emanating from Europe as it struggles to deal
with the unprecedented number of new arrival on its shores.
More than 300,000 refugees and migrants
-- most of them from Syria, Iraq and Afghanistan -- have fled to Europe via the Mediterranean Sea so far this year, compared to 219,000 for all of 2014, according to the United Nations. More than two-thirds of these people have landed in Greece.
The world was shocked and appalled by the harrowing images of a lifeless two-year-old Syrian boy
who washed up on a Turkish beach on Wednesday -- one of 12 people who died while attempting the same journey to Kos that had nearly cost Mohammed Besmar his life a week before.
Turkish President Recep Tayyip Erdogan
told CNN on Thursday that he and his family were "devastated" by Aylan Kurdi's death,
and said "the whole Western world is to be blamed" for its failure to effectively respond to the plight of refugees. image of
Tsiligeridu, a mother of three, finds Europe's handling of the refugee crisis
"infuriating," and says she never imagined her single act of kindness would prompt such an outpouring of support.
"Europe is sitting in its chair and watches the news on TV with its hands tied and not doing anything -- I believe that wide-scale drastic actions are needed.
"These are the things that the politicians have given us: fear, stress, humiliation, frustration and anger, and that's why I believe this act had such an impact," she says.
"I believe that anyone would have done the same, if they wanted to call themselves humans."