A physiotherapist braved more than 11 hours of freezing water, strong currents and jellyfish stings - all while battling a shoulder injury - to raise funds for healthcare.
Samantha Poulsen, 28, became just the 25th woman to swim across the North Channel - one of the most difficult open water swims in the world - in support of the Guys' and St Thomas' Charity.
A respiratory physiotherapist in the intensive care unit at St Thomas' Hospital, Sam completed the gruelling 21-mile swim from Donaghadee in Northern Ireland to Portpatrick in Scotland in 11 hours and 12 minutes.
Sam, who's originally from Perth in Australia and lives in Tower Hamlets, said: "I work with critically unwell patients, people whose lives have been turned upside down by sickness.
"The staff that work in the NHS put their hearts and souls into the work they do and I'm inspired by them on a daily basis.
"I am raising funds to help ease the journey of patients and their families through these incredibly trying times as well as for ongoing staff development and training."
Sam became just the second Australian woman to conquer the gruelling journey - less than one year after swimming across the English Channel.
"Although I was really lucky with the weather and the sun was shining, I found it much harder than the English Channel because the water was so cold," she said.
"I never usually struggle to stay positive during long-distance swims, but after four hours I felt really tired and at some points I didn't think I was going to make it.
"The water temperature was around 13 degrees so I tried to prepare by only taking cold showers in the six months leading up to the swim.
"It definitely helped but on the day the cold was unrelenting and debilitating so it became a real mental challenge.
"I kept going because I didn't want to disappoint anyone."
Her mum Emmy travelled from Australia to support her and was on the boat with housemate Ryan Shoesmith cheering her on.
Sam said: "When I was less than a mile from the end my mum jumped in and swam beside me.
"It was a really special and unforgettable experience to share with her.
"When we reached the rocks we hugged and cried, it was amazing."
High numbers of lion's mane jellyfish "the size of dinner plates" made the going even tougher.
Sam lost count after seeing about 70 in the first 90 minutes.
"I was stung about eight times, which felt like a burning sensation, and my forearm and hands got the worst of it because I couldn't always see the tentacles", she said.
She was also battling an old shoulder injury - after tearing her rotator cuff during the English Channel swim - which began to trouble her about four hours in.
Sam admitted some people think she is "mad" but she is proud of what she has achieved.
"Life can sometimes throw you some serious curveballs so I'm grateful for my health," she said.
"I encourage everyone to go out there and live life as best you can and try and do a little good along the way."
Sam has raised more than £2,300 for Guy's and St Thomas' Charity from the swim.
Visit uk.virginmoneygiving.com/SamanthaPoulsen to donate.
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